MONOGRAPHS  OF 
THE  ROCKEFELLER  INSTITUTE 
FOR  MEDICAL  RESEARCH 

No.  13  November  15,  1920 


THE  EARLY  STAGES  OF  TABANID^E  (HORSE-FLIES) 

By 

WERNER  MARCHAND,  Ph.D. 


NEW  YORK  ^ 

The  Rockefeller  Institute  for  Medical  Research 


Copyright,  1920,  by 

The  Rockefeller  Institute  for  Medical  Research 


WAVERLY  PRESS 
The  Williams  & Wilkins  Company 
Baltimore,  U.  S.  A. 


MONOGRAPH  No.  13 


THE  EARLY  STAGES  OF 
TABANID/E  (HORSE-FLIES) 


BY 

WERNER  MARCHAND,  Ph.D, 


NEW  YORK 

The  Rockefeller  Institute  for  Medical  Research 

1920 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/earlystagesoftab00marc_0 


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MONOGRAPH  OF  THE  ROCKEFELLER  INSTITUTE  FOR  MEDICAL  RESEARCH,  NO.  13, 
NOVEMBER  15,  1920. 


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THE  EARLY  STAGES  OF  TABANID2E  (HORSE-FLIES). 

By  WERNER  MARCHAND,  Ph.D. 

{From  ‘he  Department  of  Animal  Pathology  of  The  Rockefeller  Institute  for  Medical 

Research , Princeton , N.  J .) 

Plates  1 to  15. 

(Received  for  publication,  April  23,  1917.) 

CONTENTS. 


Introduction 

History  of  investigations 

Chronology 

Tabanidae,  description  of  early  stages 

Bionomics 

Special  anatomy  of  tabanid  larvae;  Graber’s  organ. 

Chrysops  (Meigen) , early  stages  in  general 

Chrysops  bimaculosa  Neave 

“ callidus  Osten  Sacken 

“ celer  Osten  Sacken 

“ dispar  Fabricius 

“ Indus  Osten  Sacken 

“ longicornis  Macquart 

“ magnifica , z far.  inornata,  Austen 

“ mcechus  Osten  Sacken 

“ mcerens  Walker 

“ relictus  Meigen 

“ vittatus  Wiedemann 

“ wellmani  Austen 

Dorcalcemus  fodiens  Austen 

Gastroxides  ater  Saunders 

Goniops  (Aldrich),  early  stages  in  general 

Goniops  chrysocoma  Osten  Sacken 

Hcematopota,  early  stages  in  general 

Hcematopota  crudelis  Austen 

“ decora  Walker 

insatiabilis  Austen 

“ pluvialis  Linne 

“ sp 

Hexatoma  pellucens  Linne 


4 

7 

15 

17 

27 

29 

44 

46 

46 

47 

47 

48 

48 

49 

49 

50 
52 
52 

54 

55 

55 

56 

57 
66 
66 
67 
67 
67 

73 

74 


1 


2 


THE  EARLY  STAGES  OE  TABANIDiE 


Tabanus,  early  stages  in  general 

Tabanus  albimedius  Walker 

“ atratus  Fabricius 

“ atrimanus  Loew 

“ autumnalis  Linne 

“ bicallosus  Ricardo 

“ biguttatus  Wiedemann 

“ bovinus  Linne 

“ bromius  Linne 

“ carolinensis  Macquart 

“ corax  Loew 

“ cordiger  Meigen 

“ costalis  Wiedemann 

“ desertus  Walker 

“ diteeniatus  Macquart 

“ epistates  Osten  Sacken 

“ fraternus  Macquart 

“ fronto  Osten  Sacken 

“ (Atylotus)  fulvus  Meigen 

“ fuscipes  Ricardo 

“ glaucopis  Meigen 

“ gratus  Loew 

“ hilaris  Walker 

“ ignotus  Rossi 

“ insignis  Loew 

“ kingi  Austen 

“ lasiophthalmus  Macquart 

“ laverani  Surcouf 

“ lineola  Fabricius 

“ maculatissimus  Macquart 

“ medionotatus  Austen 

“ melanoceros  Wiedemann 

“ nagamiensis  Carter 

u nigerrimus  Zetterstedt 

“ nigrescens  Palisot  de  Beauvois 

“ obscuripes  Ricardo 

“ ( Neotabanus ) ochrophilus  Lutz 

“ orientis  Walker 

u par  Walker 

“ pertinens  Austen 

“ quatuornotatus  ( quadrinotatus ) Meigen 

u semisordidus'WzAk.er 

11  solstitialis  Schiner 

“ speciosns  Ricardo 


77 

78 

79 

91 

91 

93 

94 

97 

99 

101 

101 

103 

105 

106 

106 

109 

110 

110 

111 

111 

111 

112 

112 

112 

114 

115 

119 

123 

123 

125 

126 

126 

126 

127 

127 

128 

128 

129 

129 

132 

132 

144 

144 

145 


WERNER  MARCHAND 


3 


Tabanus  spodopterus  Meigen 

“ striatus  Fabricius 

“ stygius  Say 

“ sulcifrons  Macquart 

“ tceniola  Palisot  de  Beauvois 

“ (Neotabanus)  triangulum  Wiedemann . . 

“ trimaculatus  Palisot  de  Beauvois 

“ tropicus  Linne 

“ ustus  Walker 

“ variabilis  Loew 

“ virgo  Wiedemann 

“ vivax  Osten  Sacken 

Unidentified  species  of  Tabanus 

Tabanus  sp.  No.  1 

« « u 2 

« « u 3 

« ft  a 4 

“ “ “ 5 

a n t(  g 

n « u 7 

« C(  ft  g 

« it  a g 

“ “ « 10 

a a tt  11 

“ « “ 12 

“ « « 13 

tt  it  a i4 

Parasites  of  the  early  stages  of  Tabanidse 

Hymenopterous  egg  parasites;  early  discoveries. 

Phanurus  tabanivorus,  Ashmead,  n.  sp 

“ tabani  Mayr 

“ emersoni  Girault 

Telenomus  benefactor  Crawford 

“ kingi  Crawford 

Unidentified  parasites  recorded 

Chalcid  sp.  1 


“ “ 2 

“ « 3 

Ichneumonid  sp 

Parasites  of  the  larvae 

Discussion  of  Table  II 

Table  II.  Statistical  table  of  results  on  early  stages 

Notes  on  methods  of  rearing  and  studying  tabanids  in  early  stages 

Bibliography 

Explanation  of  plates 


145 

145 

163 

167 

168 
171 
171 

171 

172 

172 

173 
173 
176 
176 
176 
176 

176 

177 

177 

178 

179 
179 
179 
179 

179 

180 
181 
182 
182 

183 

184 

185 

186 
186 
186 
186 
186 
186 
187 

187 

188 
190 
196 
200 
204 


INTRODUCTION. 


The  Tabanidae  are  a group  of  blood-sucking  insects  which,  though 
of  less  importance  to  medicine  than  mosquitoes  and  certain  groups  of 
flies,  are  nevertheless  of  sufficient  interest  to  the  student  of  animal 
pathology  to  warrant  a closer  study  and  a completion  of  our  meager 
knowledge  of  the  life  history  of  these  insects.  As  the  group  consists 
of  many  species  spread  over  all  parts  of  the  world,  it  is  natural  that 
the  work  done  hitherto  has  scarcely  advanced  beyond  the  systematic 
and  descriptive  stage;  and  the  lack  of  information  on  development  and 
early  stages  is  especially  felt  by  experimental  science.  In  fact,  al- 
though Tabanidae  play  a considerable  part  in  transmitting  diseases 
of  domesticated  animals,  and  in  spite  of  the  trouble  which  their 
presence  in  large  numbers  causes  to  horses  and  cattle  even  under 
normal  conditions,  our  knowledge  of  their  life  history  is  very  incom- 
plete compared  with  that  which  we  possess  of  other  groups  of  blood- 
sucking insects;  for  instance,  Culicidae.  Only  recently  the  study 
of  tabanid  life  histories  has  been  undertaken  from  the  point  of  view 
of  their  economic  importance,  by  King,  British  Government  Ento- 
mologist in  the  Anglo-Egyptian  Sudan,  Mitzmain  in  the  Philippine 
Islands,  and  others.  However,  these  authors  practically  ignore 
previous  or  contemporary  literature  on  the  subject  of  their  investiga- 
tion. Thus  Mitzmain  states  that  the  literature  on  the  subject  is 
meager  and  quotes  only  three  publications.  When  rediscovering 
Graber’s  organ  in  the  larvae  studied  by  him,  he  assumes  that  the  organ 
is  peculiar  to  this  species  or  has  been  overlooked  by  the  previous 
authors.  The  Zurich  Index  (Concilium  Bibliographicum),  however, 
contains  reference  to  several  publications  of  European  authors  on 
this  organ. 

I have  undertaken  a review  of  the  literature  on  the  subject  because 
the  entomological  literature  is  especially  difficult  of  access,  being 
scattered  over  a number  of  small  periodicals  appearing  in  different 
languages.  Field  and  experimental  work  on  entomological  subjects 
is  often  done  at  a great  distance  from  large  libraries,  and  it  would  be 
an  advantage  to  the  individual  worker,  especially  in  the  tropics,  to 

4 


WERNER  MARCHAND 


5 


have  all  the  facts  on  a definite  subject  concentrated  in  one  publication. 
I have  therefore  decided  to  give  not  only  a summary  of  the  literature 
with  the  bibliography,  as  is  usually  done  in  text-books,  but  also  a 
complete  report  of  all  the  facts  found  in  these  publications,  with  very 
little  change  in  the  wording,  literal  quotation  of  all  authentic  descrip- 
tions, and  with  the  reproduction  of  practically  all  the  existing  illus- 
trations on  the  subject,  sufficiently  accurate  to  make  the  consultation 
of  the  originals  unnecessary.  By  this  means  I hope  to  relieve  the 
worker  on  the  subject  in  question  of  the  necessity  of  consulting 
libraries,  except  the  future  monographer  of  the  whole  group,  who  will 
prefer  to  go  back  to  the  original  publications.  On  the  other  hand, 
as  a full  bibliography  is  given,  in  case  of  uncertainty  about  any  detail, 
the  originals  can  always  be  consulted  and  compared  with  this  report. 

There  is,  however,  another  consideration  of  some  importance  which 
has  guided  me  in  preparing  this  review;  that  is,  the  desirability  of 
having,  generally,  all  the  facts  on  one  subject  of  research  concentrated 
in  one  language,  preferably  English.  The  diversity  of  languages  is  a 
great  hindrance  for  the  progress  of  science,  and  from  the  point  of 
view  of  methodical  unification,  specialists  in  any  branch  of  science 
should  be  encouraged  to  concentrate  all  the  literature  on  their  own 
subject  in  the  language  which  they  prefer  to  have  used.  Having 
given  considerable  time  to  the  study  of  this  question,  I cannot  see 
any  serious  objection  to  the  more  general  adoption  of  English  in 
science.  It  is  to  be  hoped  that  the  temporary  disadvantages  to  the 
non-English-speaking  scientists,  resulting  from  its  adoption  would  be 
made  up  by  the  advantages  of  a great  progress  in  science  which  would 
undoubtedly  follow.  It  is  for  the  scientists  of  English-speaking 
countries  to  pave  the  way,  by  conquering  the  field  systematically, 
subject  after  subject,  and  to  facilitate  the  production  of  new  work 
by  a complete  assimilation  of  work  previously  done  in  foreign 
languages. 

I wish  to  express  my  indebtedness  to  the  authorities  of  the  American 
Museum  of  Natural  History  and  of  the  Philadelphia  Academy  of 
Natural  Science  for  giving  me  liberal  access  to  their  libraries  and 
collections,  and  to  Dr.  Theobald  Smith,  Director  of  the  Department 
of  Animal  Pathology  under  whose  guidance  this  work  was  rendered 
possible. 


6 


THE  EARLY  STAGES  OF  TAB  ANTE)  iE 


In  grouping  the  material  I have  as  far  as  possible  followed  a system- 
atic arrangement,  by  bringing  all  the  facts  which  could  be  referred 
with  certainty  to  a definite  species  under  the  heading  of  that  species, 
even  where  the  facts  appear  to  apply  to  a whole  genus  or  to  tabanids 
in  general.  In  each  species  the  egg  stage  is  first  treated,  followed  by 
the  larval  and  pupal  stages.  Results  obtained  by  one  author  in  one 
paper  have,  consequently,  often  been  separated  and  rearranged.  On 
the  other  hand,  no  attempt  has  been  made  towards  extensive  gen- 
eralization; the  general  statements  on  the  family  Tabanidae  and  the 
more  important  genera  are  only  such  as  are  found  already  in  the 
literature,  and  are  not  to  be  considered  as  final  or  as  expressions  of  the 
author’s  opinion. 

In  the  arrangement  of  the  plates  a slightly  different  plan  has  been 
followed,  as  it  seemed  desirable  to  facilitate  the  comparison  of  corre- 
sponding stages.  I have  therefore  figured  on  Plates  1 and  2 all  the 
existing  illustrations  of  the  egg  stage  of  different  species;  on  the  fol- 
lowing plates  the  larvae  and  larval  structures;  following  these  the 
pupae;  and  finally  pupal  structures,  these  being  of  especial  sys- 
tematic value.  With  this  arrangement  the  different  stages  of  the 
same  species  are  necessarily  separated  and  figured  on  different  plates. 
In  the  details,  the  arrangement  has  been  such  as  seemed  most  con- 
venient. Occasionally  an  exception  to  the  general  order  has  been  made 
and  a group  of  figures  illustrating  one  species  or  genus  appears 
on  the  same  plate. 


HISTORY  OF  INVESTIGATIONS. 


In  1760  the  Swedish  naturalist  Degeer  published  a paper,  in  the 
transactions  of  the  Swedish  Academy  of  Science,  on  the  larval  and 
pupal  stages  of  the  European  horse-fly,  Tabanus  bovinus,  which  he 
found  to  be  terrestrial  in  habit,  and  which  he  described  in  a paper 
bearing  the  title  Bromsarnas  ursprung  (The  origin  of  horse-flies). 
Degeer  was  a contemporary  and  compatriot  of  Fabricius,  the  first 
great  entomologist,  and  both  continued  the  work  of  Linne.  It  is 
stated  by  various  authors  that  Fabricius,  works  also  contain  data  on 
the  early  stages  of  Tabanidae,  though  very  few,  but  I have  not  been 
able  to  find  such  data  in  the  Sy sterna  Entomologioe  (1775)  or  in  the 
Entomologia  Systematica.  The  statement  that  the  larvae  of  Chrysops 
are  found  in  the  ground  cannot  have  been  made  by  Fabricius,  in  this 
form,  as  the  genus  Chrysops  was  first  established  by  Meigen  (1803). 
If  Zetterstedt  makes  this  statement  in  Diptera  Scandinavia , it  is  pos- 
sible that  it  is  from  verbal  information  or  from  some  later  writings  of 
Fabricius.  Zetterstedt  seems  to  doubt  it,  stating  that  he  has  seen 
large  numbers  of  newly  emerged  Chrysops  near  the  margin  of  a lake, 
which  would  indicate  an  aquatic  habitat.  The  Swedish  school  for  a 
considerable  time  dominated  entomological  work  in  all  countries 
Degeer’s  observations  are  reprinted  in  his  Memoir es  pour  servir  a 
Vhistoire  des  insectes , which  appeared  in  French  in  1776  and  also  in 
German  translation  (Goeze,  1882).  These  observations  are  given 
without  change  by  Macquart  in  Histoire  naturelle  des  insectes.  Dipteres 
(1834),  and  by  Westwood  in  England,  the  illustrator  of  the  Arcana 
Entomologica , in  his  paper  Introduction  to  the  modern  classification  of 
insects  (1840).  To  the  same  school  belongs  Wahlberg,  who  in  1838 
published,  in  Swedish,  accounts  of  the  larval  stages  and  mode  of  life 
of  many  Diptera,  which  also  contain,  according  to  Brauer,  notes  on 
tabanid  larvae  living  inside  lepidopterous  larvae,  probably  in  a pseudo- 
parasitic  way.  In  one  of  his  papers  on  this  subject  I could  not  find 
any  reference  to  Tabanidae. 

The  progress  of  entomology  consisted  chiefly  in  a greater  specializa- 
tion as  to  definite  orders  which  were  systematically  studied  and 

7 


8 


THE  EARLY  STAGES  OF  TABANID  iE 


described,  and  in  the  greater  attention  which  was  given  to  the  larval 
stages.  A new  school  of  investigation  on  this  subject  arose  in  the 
German-speaking  countries  with  Vienna  as  its  center,  where  Schiner 
had  become  an  authority  on  the  Diptera  of  Austria-Hungary,  and 
where  Brauer  devoted  himself  to  a comparative  study  of  insect  meta- 
morphosis, particularly  of  dipterous  larvae.  It  is  to  be  noted  that 
Scholtz,  in  1848,  in  Breslau,  on  an  excursion  in  which  von  Siebold  also 
took  part,  discovered  some  tabanid  larvae,  indicating  an  influence  of 
the  growing  science  of  general  zoology  on  this  subject.  In  1854 
Mann  discovered  oviposition  in  Tabanus  autumnalis , and  Kollar,  at 
the  Vienna  Museum,  observed  the  eggs  of  various  other  species  of 
Tabanus , stating  that  since  Degeer  nothing  had  been  known  about  the 
development  of  these  insects.  In  the  following  decades  great  progress 
was  made  in  the  knowledge  of  dipterous  and  other  insect  larvae, 
chiefly  through  the  Vienna  school.  In  1868  one  of  Brauer’s  students, 
Marno,  found  the  larvae  of  Hexatoma  pellucens,  a tabanid  not  rare  in 
Austria,  this  being  one  of  the  first  instances  known  of  an  aquatic 
larval  stage  in  this  family.  This  larva  was  described  more  fully  in 
1883  by  Brauer  himself.  In  1869  Brauer  was  able  to  describe  the 
larva  and  pupa  of  Hcematopota  pluvialis  (Regenbremse) , which  is 
terrestrial,  giving  at  the  same  time  a careful  drawing  of  the  mouth- 
parts  with  correct  interpretation  of  all  the  details.  At  about  the  same 
time  Brauer  was  working  on  the  classification  of  dipterous  larvae. 
The  larva  of  Hcematopota  pluvialis  was,  however,  described  also  by 
Perris  in  France  in  1870,  who  found  it  in  rotten  pine  wood,  and  gives 
a figure  showing  the  fine  striations  which  are  not  shown  in  Brauer’s 
figures;  and  the  same  larva  was  described  in  1875  by  Beling,  inspector 
of  forests  in  the  Harz  mountains,  both  apparently  independent  of 
Brauer’s  studies.  Beling  was  also  the  first  to  describe  the  pupa  of 
Chrysops,  in  1882.  On  the  other  hand,  von  Friedenfels,  who  found  the 
larva  of  Tabanus  autumnalis  in  the  salt  lakes  of  Siebenbiirgen,  belonged 
to  the  Vienna  naturalist  group,  and  the  larva  which  he  had  supposed 
to  be  an  annelid  was  identified  by  Brauer.  The  results  of  all  these 
investigations  are  briefly  summarized  by  Brauer  in  1883  in  the  third 
volume  of  Die  Zweiflugler  des  Kaiserlichen  Museums  zu  Wien,  in  which 
the  larvse  of  Tabanus  solstitialis , spodopterus,  and  bromius,  and  the 
larva  of  Hexatoma  pellucens  are  described. 


WERNER  MARCHAND 


9 


During  the  period  just  mentioned  the  microscopic  study  of  lower 
organisms  had  made  continuous  progress  and  the  anatomical  investi- 
gators soon  began  to  discover  favorable  objects  of  research  in  the 
histology  of  insects.  The  study  of  sense  organs  of  lower  animals  had 
since  Johannes  Muller  become  a favorable  subject  of  research.  On 
the  other  hand,  the  native  fresh  water  fauna  furnished  the  most  varied 
and  suitable  objects  for  microscopic  study,  and  this  fact  led  to  re- 
peated observations  on  tabanid  larvae  from  the  point  of  view  of  general 
zoology,  the  determination  of  the  species  at  hand  being  omitted  with 
an  almost  disconcerting  regularity.  We  have,  however,  noted  that 
tabanid  early  stages  were  observed  by  Scholtz  in  Breslau  in  1848,  and 
even  the  species  was  identified,  as  adults  had  hatched  from  the  pupae 
collected.  In  1878  Graber,  in  Czernowitz,  Austria,  in  his  studies  on 
the  sense  organs  of  insects,  discovered  a peculiar  otocyst-like  organ 
in  a Tabanus  larva,  called  Graber ’s  organ  by  later  authors,  a dis- 
covery which  he  connected  with  that  of  similar  organs  in  the  larva 
of  Ptychoptera  by  the  zoologist  Grobben.  His  paper  called  forth  an 
article  by  Krauss  in  1879,  a pupil  of  Brauer  in  Vienna,  according  to 
whom  this  organ  had  already  been  demonstrated  by  Brauer  in  the 
tabanid  larva  in  his  zoological  course.  Krauss  also  declared  the  larva 
defined  by  Graber  as  a fly-maggot  to  be  a Tabanus  larva,  and  to  belong 
to  Tabanus  autumnalis.  Whether  the  species  was  really  this  or  a 
similar  one,  no  one  can  say  at  present.  However,  to  Graber  belongs 
the  credit  of  the  independent  discovery  of  this  organ  and  its  minute 
description.  In  a later  work  (1882)  on  the  chordotonal  organs  of 
insects,  Graber  figured  another  tabanid  larva  with  many  anatomical 
details,  demonstrating  in  it  the  chordotonal  organs  which  had  been 
discovered  by  Leydig  in  Corethra  plumicornis.  These  discoveries, 
especially  the  otocyst-like  organ,  gave  rise  to  scientific  controversy, 
Lecaillon  in  France  (1905  and  1906)  assuming  that  the  organ  must 
in  reality  be  a gland,  while  Paoli  (1907)  in  an  extensive  work  under- 
takes to  prove  that  it  is  not  an  auditory,  but  a sound-producing  organ. 
At  the  same  time  Paoli  advanced  an  interesting  theory  about  the 
manner  in  which  the  organ  is  developed,  though  without  reference  to 
phylogeny. 

With  Lecaillon  and  Paoli  an  influence  of  economic  entomology, 
especially  of  agriculture,  is  notable  in  stimulating  research,  unques- 


10 


THE  EARLY  STAGES  OE  TABANIDiE 


tionably  a reaction  on  Europe  from  America.  In  America  research  on 
the  early  stages  of  Tabanidae  begins  with  Walsh  (1863),  who  belongs 
entirely  to  the  old  type  of  naturalist  like  Westwood  and  others,  de- 
scribing facts  of  nature  half  as  pioneers  of  discovery  in  strange  coun- 
tries, half  as  pioneers  of  religion,  and  filled  with  a deep  admiration  of 
the  wisdom  manifesting  itself  in  creation.  He  is  contemporary  with 
Osten  Sacken,  the  first  systematic  specialist  of  American  dipterology, 
who  published  his  Prodromus  to  a monograph  of  North  American 
Tabanidae.  In  Walsh’s  publication  of  previous  work  only  Degeer 
is  referred  to,  and  Walsh  believes  that  his  larva,  which  was  proved 
later  to  be  that  of  Tabanus  atratus,  was  the  first  instance  of  an  aquatic 
tabanid  larva.  In  fact,  though  the  observations  of  Wahlberg,  Zetter- 
stedt,  Scholtz,  and  Kollar  were  not  known  to  Walsh,  these  authors 
give  only  indications  but  no  full  evidence  of  aquatic  habits  of  life  of 
the  larvae  observed  by  them.  While  a member  of  the  Boston  Nat- 
ural History  Society,  Walsh  lived  for  some  time  in  Illinois,  where 
tabanids  were  numerous  and  annoying,  so  that  the  economic  side  of 
the  subject  inevitably  received  attention.  We  may  say  that  with  him 
begins  the  American  or  economic  school  of  investigations  on  this 
subject.  How  curiously  the  economic  considerations  were  mixed 
with  a profound  confidence  in  the  wisdom  of  nature  may  be  seen  from 
the  following  quotation  from  his  paper,  with  which  few  modern  in- 
vestigators will  be  found  to  agree,  except  perhaps  the  last  sentence: 

“The  scheme  of  the  creation  is  perfect,  and  nature  is  never  at  fault.  It  is 
only  when  nature’s  system  is  but  half  understood  that  we  heedlessly  complain 
of  its  imperfections.  We  blame  the  house-flies  for  annoying  us,  and  fail  to  see 
that  in  the  larva  state  they  have  cleared  away  impurities  around  our  dwellings, 
which  might  otherwise  have  bred  cholera  or  typhus  fever.  We  execrate  the 
blood-thirsty  mosquito,  and  forget  that  in  the  larva  state  she  has  purified  the 
water,  which  would  otherwise,  by  its  malarial  effluvia,  have  generated  agues  and 
fevers.  In  all  probability,  when  we  rail  at  the  Tabani,  which  torment  our  horses 
in  the  summer,  we  are  railing  at  insects  which,  in  the  larva  state,  have  added 
millions  of  dollars  to  the  national  wealth,  by  preying  upon  those  most  insidious 
and  unmanageable  of  all  the  insect  foes  of  the  farmer — subterraneous  root-feed- 
ing larvae.” 

The  larva  of  Tabanus  atratus  is  redescribed  by  C.  V.  Riley  in  1870 
in  the  second  of  his  Missouri  Reports,  this  being  the  first  publication 


WERNER  MARCH  AND 


11 


on  a tabanid  larva  issued  from  an  agricultural  institution.  Riley 
apparently  was  interested  in  all  insects  and  their  development,  and 
in  fact  included  in  his  Reports  also  some  insects  of  no  economic 
importance. 

A great  step  in  advance  was  made  when  in  1895,  Hart,  in  Illinois, 
probably  interested  by  Walsh,  who  had  lived  there,  but  probably  also 
not  without  some  knowledge  of  the  studies  of  the  Vienna  school,  under- 
took to  investigate  the  entomology  of  the  Illinois  River  on  a large 
scale.  He  described  large  numbers  of  new  dipterous  larvae,  and  inci- 
dentally a number  of  tabanid  larvae,  notably  those  of  Chrysops 
vittatus,  Tabanus  stygius,  nigrescens,  lineola,  and  costalis , which  were 
not  known  before,  and  giving  a preliminary  classification  by  which 
these  larvae  could  be  separated.  Hymenopterous  egg  parasites  of 
Tabanus , previously  seen  by  Kollar,  were  then  for  the  first  time  ex- 
actly described  by  Ashmead,  who  cooperated  with  Hart.  I do  not 
think  that  Hart  could  have  achieved  his  results  without  a knowledge 
of  Brauer’s  monograph,  which  had,  in  fact,  appeared  ten  years  before, 
and  which,  as  stated,  contains  references  to  most  of  the  previous 
work.  But  as  he,  apparently  following  Agassiz’s  principle,  “ Study 
nature,  not  books,”  makes  no  mention  of  the  previous  literature  on 
this  subject,  I assume  this  to  be  the  reason  why  later  authors,  Hine, 
and  even  Lecailion,  have  lost  the  thread  of  tradition  pertaining  to 
their  subject,  and  why  important  results  such  as  the  descriptions 
of  numerous  larvae  and  the  discovery  of  Graber’s  organ  have  been 
overlooked  by  American  and  European  authors.  Shortly  afterwards, 
in  1899,  the  insect  volume  of  the  Cambridge  Natural  History,  by 
Sharp,  appeared  in  England,  which  also  does  not  mention  the  litera- 
ture, but  contains  the  description  of  an  unknown  tabanid  larva, 
referred  to  by  Sharp  as  Tabanus  {? Atylotus  fulvus) . 

In  America  new  discoveries  of  tabanid  early  stages  were  made  by 
Hine,  who,  continuing  Osten  Sacken’s  work  in  this  field,  has  become 
the  leading  authority  on  the  Tabanidae  of  North  America,  especially 
from  the  systematic  point  of  view.  In  1903  he  described  the  life 
history  of  Tabanus  vivax ; this  paper  was  followed  by  a publication  on 
the  Tabanidae  of  Ohio,  which  also  contains  notes  on  the  early  stages. 
It  is  worthy  of  note  that  Hart’s  as  well  as  Hine’s  first  publications  were 
not  issued  by  economic  but  by  scientific  institutions  (Illinois  Biolog- 


12 


THE  EARLY  STAGES  OF  TABANIDJ5 


ical  Survey,  Ohio  Naturalist,  Ohio  Academy  of  Science);  later  the 
connection  with  agriculture  was  established,  first  in  Hine’s  Report  on 
the  Tabanidae  of  the  Gulf  Coast  (1903),  then  in  his  Habits  and  life 
histories  of  some  flies  of  the  family  Tabanidae  (1906),  in  which  the 
early  stages  of  Tabcmus  lasiophthalmus,  and  some  others,  are  given 
for  the  first  time.  The  Tabanidae,  long  known  as  a stock  pest,  were 
at  about  that  time  suspected  of  carrying  infectious  cattle  diseases 
(anthrax  and  surra),  as  was  evident  from  Salmon  and  Stiles’  Emer- 
gency report  on  surra  published  in  1902  in  connection  with  a small 
outbreak  of  surra  in  the  United  States  following  the  importation  of 
Indian  zebu  cattle.  The  interest  taken  by  entomologists  in  Hine’s 
work  called  forth  some  smaller  publications  in  America,  as  in  1908 
that  of  Walton,  containing  descriptions  of  the  early  stages  of  Goniops 
chrysocoma,  a peculiar  species,  and  in  1909  that  of  Brimley,  with  notes 
on  the  early  stages  of  several  other  Tabanidae,  one  of  them  Tabanus 
fronto,  being  terrestrial  in  habit.  On  Goniops  chrysocoma , under  the 
auspices  of  the  United  States  Department  of  Agriculture,  a more 
detailed  study  was  made  by  McAtee  in  191 1.1  On  the  other  hand, 
in  methods  of  control  of  Tabanidae,  some  progress  was  made  by  the 
work  of  Portsc'hinsky  in  Russia,  in  1908;  Lecaillon  in  1905  in  France; 
and  Paoli  in  1907  in  Florence,  also  undertook  studies  on  Tabanidae, 
which  apparently  were  stimulated  by  work  already  done  on  this  sub- 
ject in  America,  Lecaillon  referring  to  Hart,  and  Paoli,  while  resuming 
the  problem  of  Graber’s  organ,  working  at  an  agricultural  school  where 
he  undoubtedly  received  Hine’s  publications.  Lecaillon’s  work  (1905), 
which  acquaints  us  with  the  egg-laying  habits  of  Tabanus  quatuorno- 
tatus , cites  the  observations  on  this  species  made  by  Kollar  in  1854. 
The  progress  made  in  the  meantime  by  the  Vienna  school  is,  however, 
ignored  by  him,  which  we  understand  if  we  realize  that  the  wars  of 
1866  and  1870  had  destroyed  cooperation  to  some  extent.  The  only 
new  author  cited  by  Lecaillon  is  Hart,  who,  as  we  have  stated,  did 
not  quote  the  literature.  At  the  same  time,  Lecaillon  (1905)  and 
Hine  (1906)  are  perhaps  the  first  writers  in  whom  the  influence  of 
medicine  on  entomology  is  perceptible.  The  part  that  insects  play 
in  the  transmission  of  disease,  the  theory  of  which  is  intimately  con- 


1 Specimens  of  the  larva  of  this  species  had  been  found  before  by  Pergande. 


WERNER  MARCHAND 


13 


nected  with  the  discoveries  of  Theobald  Smith  (1893),  Bruce  (1895), 
Ross  (1897),  Grassi  (1900),  and  Reed  (1901),  had  attracted  attention 
to  all  blood-sucking  insects  as  possible  carriers,  and  the  influence  on 
the  study  of  Tabanidae  showed  itself  in  the  progress  of  knowledge  of 
their  early  stages.  In  the  following  period  extending  up  to  the 
present,  studies  on  these  have  been  made  largely  under  the  auspices 
of  medical  entomology.  The  progress  resulting  is  considerable,  the 
number  of  publications  on  the  subject  within  the  last  fifteen  years 
being  about  equal  to  that  of  papers  published  previous  to  1900. 

To  the  interest  aroused  in  the  study  of  Tabanidae  from  the  medical 
point  of  view  we  owe  in  the  first  place  a knowledge  of  life  histories  of 
tabanids  of  tropical  countries,  chiefly  Africa  and  India,  where  the 
importance  of  these  flies  as  carriers  of  disease  is  paramount.  In  1908 
King  was  sent  by  the  British  Government  to  the  Sudan  in  charge  of 
economic  entomology  in  the  Wellcome  Research  Laboratory  in  Khar- 
toum. He  goes  into  the  subject  more  extensively  than  any  of  the 
previous  authors,  working  out  the  life  history  of  the  black  African 
horse-fly,  Tabanus  biguttatus  (1908)  and  of  Tabanus  ditceniatus , 
taniola , kingi,  and  par  (1910),  succeeding  for  the  first  time  in  causing 
tabanids  to  oviposit  in  captivity,  and  giving  minute  descriptions  of 
larval  structures,  which  appear  cumbersome  but  may  well  serve  to 
separate  the  species  described  from  others  not  yet  known.  At 
about  the  same  time  we  learn  of  tabanid  larvae  in  India  from  Maxwell- 
Leffroy  and  Howlett,  Indian  insect  life  (1909),  a work,  however, 
written  more  from  the  point  of  view  of  agricultural  interests,  while 
Baldrey  and  Mitzmain  studied  tabanids  in  captivity  with  the  imme- 
diate object  of  determining  their  part  as  carriers  of  disease.  Baldrey 
(1911-12)  had  Tabanus  orientis  oviposit  in  captivity,  but  made  no 
observations  on  the  larvae.  Mitzmain  has  made  a very  complete  in- 
vestigation on  the  life  history  of  a single  tabanid  species,  Tabanus 
striatus  (1913).  Mitzmain  worked  in  the  Philippine  Islands  and  dem- 
onstrated experimentally  the  transmission  of  surra  (1913)  and  anthrax 
(1914)  by  this  species.  His  omission  of  reference  to  previous  litera- 
ture has  been  commented  upon,  but  as  his  work  was  done  far  away 
from  large  libraries  he  was  naturally  handicapped  in  this  respect. 
While  Mitzmain  raised  his  flies  entirely  in  captivity,  Bainb ridge 
and  Fletcher  (1914)  reported  the  oviposition  of  the  same  species  in  the 


14 


THE  EARLY  STAGES  OF  TABANIDiE 


free-living  state.  The  text-book  of  medical  entomology  by  Patton 
and  Cragg  (1913),  who  worked  in  Madras,  again  gives  descriptions 
of  egg  and  larval  stages  of  various  Indian  tabanids,  with  information 
on  habits,  methods  of  rearing,  etc.,  giving  also  for  the  first  time  a 
more  complete  idea  of  work  previously  done.  The  organ  discovered 
by  Graber  (1878)  is  illustrated  and  discussed  by  these  authors; 
Paoii’s  work  on  the  same  subject,  however,  seems  to  have  remained 
unknown  to  them.  At  about  the  same  time  (1914)  Lutz  in  Rio  de 
Janeiro  published  the  first  meager  observations  on  early  stages  of 
tabanids  in  Brazil,  having  found  larvae  of  Tabanus  ( Neotabcmus ) 
ochrophilus  and  triangulum , and  of  one  undetermined  species.  The 
studies  of  Neave  in  the  following  year,  1915,  furnish  abundant  infor- 
mation on  early  stages  of  African  tabanids,  and  new  studies  on  South 
American  tabanid  larvae  were  published  by  Bodkin  and  Cleare  in 
1916.  Some  new  species  of  egg  parasites  have  also  been  described  in 
recent  years  by  Crawford  from  King’s  material,  and  by  Girault  (1916) 
from  Tabanus  eggs  from  Dallas,  Texas. 

The  various  text-books  on  medical  entomology  and  related  subjects 
which  have  appeared  recently,  besides  those  quoted  by  Bainb ridge 
and  Fletcher  and  by  Patton  and  Cragg,  those  published  by  Goldi 
(1913),  Herms  (1915),  W.  A.  Riley  and  Johannsen  (1915),  and 
Grunberg  (1907),  also  Brumpt’s  Precis  de  parasitologie  (1910),  con- 
tain a good  deal  of  information  on  tabanid  early  stages,  including  also 
quotations  from  previous  literature. 

While  most  of  the  recent  work  has  been  done  by  British  and  Amer- 
ican authors,  new  and  accurate  studies  on  the  oviposition  of  Tabanus 
quatuornotatus  have  been  made  by  Lecaillon  (1911),  and  another 
paper  by  Picard  and  le  Blanc  (1913)  reports  the  early  stages  of  another 
species.  In  the  latter  year  there  also  appeared  a paper  by  del 
Guercio  on  the  tabanids  of  the  rice  fields  of  Bologna,  which,  however, 
contains  little  of  scientific  value. 

The  complaint  made  by  some  writers  of  the  meagerness  of  our 
knowledge  of  the  life  history  of  this  group,  notably  by  Goldi,  will 
probably  soon  be  unfounded,  if  our  knowledge  progresses  as  rapidly 
as  it  has  in  the  last  few  years. 

South  America,  which  is  extremely  rich  in  interesting  tabanids, 
and  Australia,  where  until  now  apparently  no  work  has  been  done, 


WERNER  MARCHAND 


15 


should  yield  many  new  discoveries.  On  the  other  hand,  European 
investigators  have  neglected  the  Tabanidae  somewhat,  and  it  would 
seem  desirable  to  reinvestigate  the  larvae  of  the  common  Tab  anus 
bovinus , which  since  their  discovery  by  Degeer  in  1760  apparently 
have  not  been  found  again. 

CHRONOLOGY. 

1760.  Degeer  bred  Tabanus  bovinus  from  terrestrial  larva. 

1775.  Fabricius’  Systema  entomologiae,  said  to  contain  notes  on  Chrysops 

larva. 

1776.  French  translation  of  Degeer’s  Memoires. 

1798.  Fabricius’  Entomologia  systematica. 

1834.  Macquart  cited  the  observations  of  Degeer. 

1838.  Wahlberg,  in  Sweden,  published  notes  on  the  larvae  as  semiparasites. 
1840.  Westwood  cited  the  observations  of  Degeer. 

1842.  Zetterstedt’s  observations  on  Chrysops. 

1848.  Scholtz  observed  pupae  of  three  tabanid  species  near  Breslau. 

1854.  Kollar  published  Mann’s  observations  on  oviposition  of  Tabanus. 

1863.  Walsh,  in  Boston,  described  the  larva  of  Tabanus  atratus  (aquatic). 

1868.  Marno,  in  Vienna,  found  the  aquatic  larva  of  Hexatoma  pellucens. 

1869.  Brauer  described  the  terrestrial  larva  of  Hcematopota  pluvialis. 

1870.  Perris,  in  France,  independently  described  the  same  larva. 

1870.  Riley,  in  America,  redescribed  the  larva  of  Tabanus  atratus. 

1875.  Beling,  in  Germany,  described  (third)  the  larva  of  Hcematopota. 

1878.  Graber  discovered  an  otocyst-like  organ  in  the  tabanid  larva. 

1879.  Krauss  claimed  the  discovery  for  Brauer. 

1880.  von  Friedenfels  found  aquatic  larva  of  Tabanus  autumnalis  in  salt  lakes  in 

Siebenbiirgen. 

1882.  Beling  described  the  pupa  of  Chrysops  relictus. 

1882.  German  translation  of  Degeer’s  Memoires. 

1882.  Graber  described  the  chordotonal  organs  of  Tabanus  {Chrysops?)  larva. 

1883.  Brauer  gave  notes  and  illustrations  on  various  tabanid  larvae  and  briefly 

summarized  the  literature. 

1895.  Hart,  in  Illinois,  described  several  American  species  of  tabanid  larvae, 
notably  Tabanus  stygius,  lineola,  co stalls,  and  Chrysops  vittatus. 

1899.  Sharp,  in  The  Cambridge  Natural  History,  illustrated  larvae  of  Tabanus 
{?Atylotus  fulvus). 

1903.  Hine,  in  Ohio,  described  the  larva  and  pupa  of  Tabanus  vivax. 

1903.  Hine’s  Monograph  on  the  Tabanidae  of  Ohio,  with  notes  on  life  histories, 

containing  also  the  first  notes,  and  on  oviposition  in  Chrysops. 

1904.  Hine’s  studies  at  the  Gulf  Biological  Station. 


16 


THE  EARLY  STAGES  OR  TABANIDiE 


1905.  Lecaillon,  in  France,  gave  detailed  studies  on  the  oviposition  of  Tabanus 

quatuornotatus. 

1903-06.  Hjne’s  Gulf  Biological  Station  Reports,  containing  new  data  on 
oviposition. 

1906.  Hine’s  Report  to  the  United  States  Department  of  Agriculture,  describ- 

ing early  stages  of  Tabanus  lasiophthalmus,  sulcifrons  (in  part),  etc. 

1907.  Paoli,  in  Florence,  continued  the  work  of  others  on  Graber’s  organ. 

1908.  Portschinsky,  in  Russia,  summarized  the  previous  knowledge  of  tabanid 

life  histories,  as  an  aid  in  the  study  and  control  of  these  insects. 

1908.  King,  in  Khartoum,  described  the  early  stages  of  Tabanus  biguttatus. 

1908.  Walton,  in  Pennsylvania,  described  the  egg  and  larva  of  Goniops 

chrysocoma. 

1909.  Brimley,  in  North  Carolina,  published  notes  on  the  larvae  of  Tabanus 

fronto  and  other  species. 

1909.  Maxwell-Leffroy  and  Howlett,  in  Indian  insect  life,  gave  notes  Oh  the 

larval  habits  of  Indian  tabanids. 

1910.  McAtee,  in  Washington,  described  further  stages  of  Goniops. 

1910.  King,  in  Khartoum,  published  the  life  histories  of  Tabanus  par , tceniola, 

ditaniatus,  and  kingi,  securing  oviposition  in  captured  specimens. 

1911.  Lecaillon  gave  additional  studies  on  Tabanus  quatuornotatus. 

1911-12.  Baldrey  observed  oviposition  of  Tabanus  orientis. 

1913.  Mitzmain  published  the  life  history  of  Tabanus  striatus,  the  carrier  of 
surra  in  the  Philippines. 

1913.  del  Guercio,  in  Italy,  reported  on  the  larva  of  Tabanus  ignotus. 

1913.  Picard  and  le  Blanc,  in  France,  observed  the  larva  of  Tabanus  cordiger. 

1913.  Patton  and  Cragg  published  a text-book  of  medical  entomology,  contain- 

ing information  on  the  larvae  of  several  Indian  tabanids. 

1914.  Bainbridge  and  Fletcher,  in  India,  gave  additional  notes  on  Tabanus 

striatus. 

1914.  Lutz,  in  Rio  de  Janeiro,  described  the  larvae  of  three  Brazilian  tabanids. 

1915.  Neave  presented  abundant  data  on  the  larval  and  pupal  stages  of  African 

tabanids. 

1915.  Riley  and  Johannsen,  published  a text-book,  containing  a few  new 

illustrations. 

1916.  Girault  described  a new  egg  parasite  ( Phanurus  emersoni). 

1916.  Bodkin  and  Cleare  published  notes  on  the  early  stages  of  tabanids  in 
British  Guiana. 


TABANID^),  DESCRIPTION  OF  THE  EARLY  STAGES. 


The  Tabanidae  belong  ecologically  to  the  so  called  hydrophytic  area, 
as  has  been  pointed  out  by  Osburn.  On  the  whole,  they  may  be  called 
aquatic  or  semiaquatic,  though  not  all  of  them  pass  their  larval  stage 
actually  in  the  water;  at  the  same  time  they  show  traces  of  an  adapta- 
tion to  plants  which  may  serve  to  understand  their  phylogeny.  The 
larvae  may  be  aquatic,  semiaquatic,  or  even  terrestrial  in  habitat, 
but  always  live  more  or  less  hidden  and  are  seldom  seen.  They  are, 
according  to  Malloch,  “ found  rarely  among  decaying  leaves  or  in  low 
and  somewhat  marshy  spots  in  fields.”  Neave  and  others,  however, 
have  obtained  them  in  quantity  from  the  muddy  banks  of  rivers  and 
brooks. 

The  eggs  are  laid  in  clusters  of  one  or  several  layers,  forming  a com- 
pact flat  or  conical  mass;  they  are  rarely  laid  scattered,  and  never 
singly.  The  clusters  may  consist  of  several  hundred  eggs,  the  eggs 
being  held  together  by  a sticky  substance.  The  whole  mass  is  often 
covered  with  a dark  shining  varnish  or  with  a chalky  substance. 
These  masses  are  deposited  usually  on  plants  or  sticks  at  the  edge  of 
ponds,  streams,  and  lakes,  seldom  on  dry  ground,  and  sometimes  also 
on  stones  above  water,  but  this  is  unusual.2  The  single  egg  is  spindle- 
shaped  or  cylindric,  and  narrowed  at  the  ends,  white,  yellow,  or  pale 
brownish  when  first  laid,  but  later  often  pigmented,  brown  or  shining 
black,  the  color  being  due  to  a pigmentation  of  the  chorion.  The 
period  of  incubation  is  short,  from  3 to  9 days,  but  in  some  cases  the 
hatching  process  is  delayed  for  weeks  by  atmospheric  conditions,  while 
the  embryo  is  fully  developed  and  may  be  caused  to  hatch  by  artificial 
stimuli.  All  the  eggs  usually  hatch  at  the  same  time,  the  young 
larvae  at  first  sticking  together  but  soon  losing  their  hold  and  tumbling 
down.  In  many  cases  only  part  of  the  eggs  of  one  mass  give  birth  to 
larvae,  about  half  of  them  being  infected  by  small  hymenopterous 
parasites. 

2 Macquart’s  statement  that  the  female  deposits  its  eggs  in  the  ground  is 
erroneous. 


17 


18 


THE  EARLY  STAGES  OF  TABANID  2E 


The  newly  hatched  larvae  drop  into  the  water  or  onto  the  ground, 
according  to  the  egg-laying  habits  of  the  species,  and  little  is  known 
about  them.  The  young  larvae  resemble  the  full  grown  in  appearance, 
but  are  generally  more  transparent,  showing  the  internal  organs,  a 
pair  of  black  eye-spots,  and  Graber’s  organ  in  its  primary  condition, 
which  is  later  described.  The  chordotonal  organs  have  been  described 
in  young  tabanid  larvae.  The  nervous  system  is  clearly  visible.  The 
young  larvae  may  be  fed  on  tiny  crustaceans,  crushed  insect  larvae,  etc., 
but  are  not  always  successfully  reared. 

Of  the  young  larvae  some  have  strongly  developed  tracheal  trunks 
which  enable  them  to  float,  while  others  sink  to  the  bottom. 

All  tabanid  larvae  are  highly  predacious,  feeding  on  other  insect 
larvae,  earthworms,  and  probably  all  animals  they  can  get  hold  of, 
not  sparing  their  own  kind.  Wahlberg  found  them,  according  to 
Brauer,  semiparasitic  in  lepidopterous  (noctuid)  larvae.  Perris 
reports  that  he  has  found  them  under  stones  feeding  on  larvae  of 
Rhizotrogus  and  on  Melolontha  (imago?).  According  to  Brauer, 
young  larvae  burrow  into  other  larvae  (of  beetles)  and  leave  these 
only  when  they  completely  fill  the  skin  of  the  host.  Brauer  once 
obtained  the  larva  of  Hcematopota  from  the  larva  of  Relops  lanipes, 
from  which,  as  it  seemed  to  be  molting,  the  tabanid  larva  made  its 
way.  Walsh  states  that  they  feed  on  snails;  Hine  and  others  fed  them 
on  earthworms.  Young  larvae  can  be  fed  on  small  crustaceans 
(King).  It  is  not  known  what  food  they  take  in  nature,  and  also 
whether  they  can  subsist  on  vegetable  food.  Del  Guercio’s  statements 
on  this  point  are  probably  erroneous.  Mitzmain  and  others  have 
observed  their  cannabalistic  tendency,  at  least  in  captivity.  As  Pat- 
ton and  Cragg  have  stated,  the  larvae  of  the  large  species  and  of 
the  nearly  allied  full  grown  stages  of  the  smaller  species  feed  almost 
exclusively  on  earthworms  whose  body  juices  they  suck  out;  this 
explains  why  gregarine  cysts  (. Monocystis ) are  not  uncommonly  found 
in  the  alimentary  tract  of  the  imago.  Malloch  says  that  the  food  of 
the  species  occurring  in  rivers  is  mostly  tipulid  and  other  larvae  which 
burrow  in  the  soft  banks  of  the  rivers  or  occur  in  the  river  bottom  or 
in  drift. 

Structure  of  the  Mature  Larva. — All  the  known  larvae  of  tabanids, 
with  the  exception  of  the  somewhat  aberrant  Gonoips,  are  elongate, 


WERNER  MARCHAND 


19 


cylindric,  slender,  tapering  at  both  ends,  capable  of  contraction  and 
extension,  their  body  consisting  of  a head  and  twelve  segments,  the 
last  segment  being  very  short.  The  larvae  are  eucephalous,  with  head 
well  developed  but  small,  bearing  the  three-jointed  antennae,  at- 
tached to  the  anterior  angles  of  the  head  just  above  the  palpi,  the 
basal  joint  being  short,  the  others  of  varying  length.  A bunch  of 
stiff  spines,  either  short  or  moderately  long,  is  situated  above  each 
antenna  and  on  each  side  of  the  labrum.  All  the  essential  mouth- 
parts  are  present  and  have  been  studied  in  many  species.  They  are 
well  adapted  for  seizing  the  prey,  and  constitute  a very  formidable 
apparatus  (Patton  and  Cragg).  The  essential  organs  are  the  man- 
dibles and  first  maxillae,  and  of  these  the  former  are  the  most  powerful 
weapons.  Each  mandible  is  a stout  rod  of  chi  tin,  slightly  expanded 
at  the  base,  to  which  the  muscles  are  attached,  and  narrowed  distally 
to  a blunt  point;  the  rod  is  curved  downwards  and  forward,  and  on 
its  concave  border  has  many  coarse  serrations.  The  maxillae  are 
similar  in  shape  and  general  disposition,  but  are  smaller  and  less 
heavily  pigmented,  and  are  more  pointed.  Both  pairs  of  appendages 
can  be  thrust  out  from  the  head  in  a downwards  and  forward  direc- 
tion when  the  larva  attacks  its  prey,  by  means  of  the  protractor  and 
retractor  muscles  attached  to  the  base  of  the  rods.  One  sometimes 
becomes  aware  of  the  existence  of  these  organs  when  handling  the 
larvae,  as  they  are  used  in  defense  as  well  as  in  attack,  and  are  cap- 
able of  inflicting  a sharp  nip,  though  they  do  not  draw  blood.  The 
maxillary  palpi  are  simple  and  two-jointed,  the  distal  joint  being 
much  smaller  than  the  proximal  one.  The  dorsal  and  distal  ex- 
tremity of  the  head  is  projected  forward  as  a short  and  fleshy  labrum. 
A labium  is  likewise  present.  The  head  is  attached  firmly  to  the 
pharynx,  and  is  retracted  and  exserted  together  with  it.  The  pharynx 
itself  is  an  elongate  chamber  of  the  usual  type  and  is  easily  seen  in 
the  living  larva.  The  eye-spots  are  placed  on  the  dorsal  side  of 
the  pharynx,  not  on  the  outer  cuticle,  and  follow  the  movements, 
of  the  pharynx.  The  pharynx  leads  posteriorly  to  the  esophagus, 
which  is  narrow,  but  wider  and  more  muscular  than  that  of  the  adult. 
It  is  usual  to  find  that  the  esophagus  is  wider  and  more  muscular  in 
insects  whose  food  is  solid  or  semisolid  than  in  those  which  take  only 
fluid  food. 


20 


THE  EARLY  STAGES  OF  TABANHD^E 


The  head  itself,  as  far  as  it  can  be  exserted,  is  strongly  chitinized 
and  usually  brownish  in  color,  while  the  rest  of  the  body  is  generally 
pale,  whitish  or  grayish,  but  in  many  species  marked  with  a regular 
dark  pattern,  which  in  others  may  be  absent.  Following  the  head 
are  the  three  thoracic  segments,  of  which  the  first  is  the  shortest, 
and  these  are  followed  by  nine  abdominal  segments,  the  last  one 
forming  the  respiratory  tube,  and  the  next  to  the  last  segment  bear- 
ing ventrally  the  anus  on  a fleshy  prominence.  The  body  surface  is 
generally  smooth,  well  chitinized,  and  half  transparent.  The  fourth 
to  tenth  segments  are  provided  at  their  anterior  margin,  or  not  far 
from  it,  with  a strong  circular  fleshy  ridge,  containing  circular  muscles, 
and  bearing  the  parapodia,  eight  in  number  when  all  are  present,  or 
fewer  if,  as  may  be  the  case,  the  dorsal  ones  are  lacking.  The  ventral 
parapodia  are  usually  better  developed  and  placed  somewhat  closer 
together.  The  parapodia  may  be  retracted  and  exserted,  and,  pro- 
vided with  many  curved  spines  outwardly,  play  a part  in  locomotion. 
The  ridges  in  some  species  are  not  very  prominent,  are  usually  cov- 
ered with  a fine  pubescence  rendering  part  of  the  body  surface  opaque, 
and  are  often  pigmented  dark,  forming  the  patterns  spoken  of.  The 
spinous  processes  of  the  prolegs  pass  through  imperceptible  gradations 
into  the  fine  pubescence  of  the  dull  or  pigmented  areas. 

The  larva  of  Goniops  chrysocoma  differs  in  appearance  from  the 
other  known  tabanid  larvae  by  being  apparently  much  shorter  and 
thicker  in  the  posterior  half  of  the  body  than  in  the  anterior  where 
the  segments  are  much  tapered  and  considerably  longer,  but  as  the 
figures  are  based  on  specimens  preserved  in  alcohol,  we  cannot  pass  a 
definite  judgment  on  their  systematic  position.3 

Integument. — The  integument  in  general  can  be  divided  into  more 
or  less  distinct  dorsal,  ventral,  and  lateral  areas,  which  differ  in  their 
finer  structure,  all  being  either  longitudinally  striated  or  more  or  less 
smooth  and  shining.  The  lateral  areas  may  be  subdivided  into  an 
upper,  middle,  and  lower  portion,  marked  off  from  one  another  and 
slightly  differing  in  structure.  All  these  structural  features  of  the 
surface  of  the  integument  are  probably  vestigial'  traces  of  formerly 
more  marked  characteristics,  and  are  important  in  any  effort  to  sepa- 
rate different  species  of  larvae. 

3 See  also  Goniops  in  general,  p.  56. 


WERNER  MARCHAND 


21 


The  structure  of  the  chitinous  membrane  has  been  studied  in  de- 
tail by  Lecaillon  in  Tabanus  quatuornotatus  Meig.  The  membrane 
consists  of  three  layers  or  zones,  the  innermost  soft  and  of  greatest 
thickness,  the  two  outer  ones  hard  and  elastic ; of  the  latter  the  inner 
(median)  is  much  thicker  than  the  external  one.  By  staining  methods 
the  three  layers  can  be  differentiated.  The  fine  striation  of  the 
cuticle  is  formed  by  the  median  layer,  which  is  thickened  in  the  form 
of  narrow  longitudinal  ridges.  The  hairs  are  formed  exclusively  of 
the  external  layer.  The  muscles  to  the  integument  are  attached  to 
the  median  zone. 

The  muscular  system  is  strongly  developed,  consisting  of  the  re- 
tractor and  extensor  muscles  of  the  head,  and  probably  similar  muscles 
governing  the  retraction  and  extension  of  the  syphon;  also  of  muscle 
fibers  arranged  more  or  less  vertically  to  the  integument,  and  circular 
muscles  which  function  in  the  contraction  of  the  circular  segmental 
ridges  and  the  retraction  and  exsertion  of  the  parapodia.  The  mus- 
cular system  is  partly  illustrated  but  not  described  by  Graber  (1882) 
(Plate  8,  Fig.  100,  a).  Lecaillon  (1906)  notes  the  muscular  inser- 
tions in  the  integument,  stating  that  the  muscles  pass  through  the 
inner  chitinous  layer,  losing  here  their  transverse  striation,  and  being 
inserted  in  the  median  layer.  Various  muscles  go  to  the  organ  of 
Graber,  described  later,  by  means  of  which  this  organ  is  displaced  in 
various  directions.  (Plate  9,  Figs.  104  to  106,  and  Plate  10,  Figs. 
112,  115,  and  116.) 

Alimentary  Canal  (Plate  7,  Fig.  98). — This  has  been  studied  by 
Patton  and  Cragg  in  Tabanus  albimedius  (also  in  other  species?).  It 
is  much  shorter  and  less  complicated  than  that  of  the  larva  of 
Stomoxys  calcitrans,  described  by  the  same  authors.  The  esophagus 
opens  into  a short,  cylindric  proventriculus,  which  is  also  a highly 
muscular  structure,  and  is  sharply  distinguished  from  the  succeeding 
part  of  the  gut  by  its  clear  translucent  appearance  in  the  fresh  con- 
dition. The  mid  gut  extends  from  the  proventriculus  to  the  hind 
end  of  the  body;  and  is  thrown  into  one  or  two  simple  coils,  not  con- 
stant in  their  position.  It  is  separated  from  the  proventriculus  by  a 
short  constriction,  and  is  again  constricted  at  the  posterior  end,  just 
anterior  to  the  opening  of  the  Malpighian  tubes.  Between  these 
points  the  lumen  is  wide  and  is  thrown  into  numerous  sacculation s 


22 


THE  EARLY  STAGES  OF  TABANIDiE 


by  the  contractions  of  the  muscle  fibers  in  the  wall.  The  mid  gut 
is,  at  least  in  the  species  studied  by  Patton  and  Cragg,  of  a strik- 
ing orange-red  color  in  the  fresh  condition,  and  is  filled  with  a semi- 
solid mass  of  a light  chocolate  color,  which  oozes  out  if  the  wall  is 
punctured  in  dissecting.  The  hind  gut  is  short  and  simple,  and  is 
coiled  up  in  the  posterior  end  of  the  abdomen.  The  total  length 
of  the  gut  is  about  twice  the  length  of  the  body  of  the  larva.  The 
salivary  glands  are  simple  and  tubular,  and  bear  a remarkable  resem- 
blance to  those  of  the  adult  insect. 

Respiratory  System. — The  respiratory  system  resembles  that  of  the 
mosquito  larva.  There  are  two  large  lateral  tracheae  which  run  the 
whole  length  of  the  body  on  each  side  of,  and  slightly  dorsal  to  the 
alimentary  canal.  According  to  Patton  and  Cragg  (1913),  these 
communicate  with  the  external  air  through  an  opening,  which  can  be 
closed,  on  a small  prominence  on  the  dorsal  surface  of  the  penultimate 
segment.  This  statement  appears  to  be  erroneous.  Brauer  (1883) 
states  that  the  tabanid  larvae  are  usually  metapneustic,  the  last 
segment  with  a vertical  respiratory  fissure  or  the  last  two  segments 
forming  a respiratory  tube.  According  to  Malloch  (1917),  they  are 
always  metapneustic.  The  respiratory  tube  is  of  varying  length, 
sometimes  very  short,  sometimes  more  slender  and  tube-like,  or  form- 
ing a short  acute  spine.  The  two  main  air-filled  trunks  are  much  in- 
flated in  some  species,  enabling  the  larvae  to  float  at  the  surface  of 
the  water,  and  narrow,  almost  filiform  in  other  species.  As  they  pass 
forward,  they  give  off  slender  branches  of  tracheae  to  the  body  cavity 
in  each  segment.  In  the  anterior  part  of  the  body  the  tracheal 
stems,  in  the  species  where  they  are  generally  much  inflated,  become 
slender,  describing  one  or  several  semicircular  loops  and  tapering  into 
fine  tracheae  going  to  various  organs.  The  tracheal  branches  going 
to  the  body  wall  of  each  segment  may  be  homologous  with  those 
leading  to  the  abdominal  spiracles  in  amphipneustic  larvae. 

Dorsal  Blood  Vessel. — The  dorsal  blood  vessel  is  easily  seen  in  trans- 
parent larvae  and  ends  blind,  in  the  cases  observed,  before  the  elev- 
enth segment. 

Malpighian  Tubes. — The  Malpighian  tubes  are,  to  judge  from 
Patton  and  Cragg’ s figures,  four  in  number,  in  young  larvae  irregu- 
larly crowded  in  the  posterior  part  of  the  body  between  the  two 
tracheal  trunks,  and  of  brownish,  greenish,  or  yellow  color. 


WERNER  MARCHAND 


23 


Fat  Body. — No  observations  of  the  fat  body  have  been  made,  ex- 
cept that  Graber  (1878)  describes  it,  in  Tabanus  autumnalis  (?),  as  a 
network  of  pale  lobes  and  trabeculae  with  dendritic  tracheal  expansions, 
lying  dorsally  and  above  the  new  organ  described  by  him. 

Gonads. — These  organs,  which  must  be  present  in  the  larva,  have 
not  been  noticed  or  described  by  any  author. 

Nervous  System. — The  nervous  system  of  the  larva  consists,  ac- 
cording to  Graber,  who  studied  the  young  larva  of  Tabanus  {Chry- 
sops  ?),  of  a large  upper  and  lower  cephalic  ganglion,  and  a chain  of 
large  ganglia  arranged  like  beads  and  extending  about  half  the  body 
length.  According  to  Graber,  this  would  be  the  only  instance  of  the 
nervous  system  having  this  structure  (Plate  8,  Fig.  99). 

Sense  Organs. — The  eyes  have  been  mentioned ; their  function  is  not 
clearly  understood.  Antennas  and  palpi  are  probably  olfactory. 
Tactile  bristles  occur  on  the  body  surface  and  have  been  studied  by 
Graber  who  finds  them  connected  with  several  ganglion  cells  (Plate 
8,  Fig.  100,  b).  Chordotonal  organs,  similar  to  those  in  Corethra , 
are  found  laterally  in  each  segment  near  the  surface  of  the  integu- 
ment, and  are  of  the  mono-,  di-,  and  triscolop  type  (Graber),  and  are 
connected  with  the  tracheae.  According  to  Graber,  in  small  larvae, 
the  chitinous  body  walls  themselves  act  as  a tympanum,  thus  ex- 
plaining the  absence  of  any  special  tympanal  apparatus  (Plate  8, 
Fig.  100,  a). 

At  the  posterior  end  of  the  larva,  situated  dorsally  and  adjacent 
to  the  blind  posterior  end  of  the  heart,  on  the  eleventh  segment,  is 
an  organ  of  unknown  function,  called  Graber’ s organ,  after  its  dis- 
coverer (1878).  It  consists  of  a pear-shaped  sac,  the  broader  end  of 
which  is  anterior;  the  posterior  end  narrows  down  to  a fine  tubule 
which  opens  on  the  integument  of  the  body  between  the  last  and  the 
next  to  the  last  segments.  Within  this  sac  there  is  a series  of  capsules 
set  one  behind  the  other  in  the  long  axis,  and  within  each  of  these 
capsules  is  a pair  of  small,  black,  pyriform  bodies,  each  attached  to  the 
anterior  side  of  the  capsule  by  a delicate  pedicel  (Plate  9,  Figs.  103  to 
108,  and  Plate  10,  Figs.  109  to  120).  These  bodies  diminish  in  size 
from  the  anterior  end,  the  first  being  considerably  larger  than  the 
rest.  They  are  easily  seen  through  the  integument  of  the  living 
larva.  The  outer  sac  is  an  invagination  of  the  integument,  and  as 


24 


THE  EARLY  STAGES  OF  TABANIDiE 


such  has  a chitinous  lining.  Graber  believed  that  the  structure  is 
an  auditory  organ,  but  Lecaillon  supposed  it  to  be  a gland.  Berlese, 
according  to  Patton  and  Cragg,  does  not  consider  that  it  has  been 
proved  to  be  a sense  organ,  though  it  is  well  supplied  with  nerves. 
Paoli  has  shown  that  the  young  larva  has  only  two  pedunculate 
bodies,  and  that  with  each  successive  molt  a new  capsule  with  two 
more  such  bodies  is  formed.  Having  observed  that  Tabanus  larvae 
are  able  to  produce  a slight  crackling  noise,  Paoli  believes  the  struc- 
ture to  be  a sound-producing  organ,  but  it  is  difficult  to  understand 
what  ecological  meaning  such  an  organ  could  have.4 

The  pupae  of  tabanids  are  classified  as  orthorhaphous  (Brauer), 
opening  in  the  act  of  hatching  with  a dorsal  longitudinal  slit.  They 
strongly  resemble  lepidopterous  pupae  ( Mumienpuppe , pupa  ob tecta), 
having  wing  and  leg  cases  firmly  attached  to  the  body  and  covered 
with  it  by  a chitinous  membrane.  The  pupal  body  is  subcylindric, 
abruptly  pointed  or  rounded  anteriorly,  and  tapering  somewhat  poste- 
riorly; it  is  generally  yellowish  brown  to  ferruginous  brown,  finely 
wrinkled,  and  has  a lateral  tuft  of  hairs  on  each  abdominal  segment. 
On  either  side  of  the  head  are  the  antennal  sheaths,  pointing  outwards, 
and  on  each  side  of  the  median  line  two  large  tubercles,  each  with  a 
central  hair;  below  these  are  two  raised  areas  with  sharp  edges,  sepa- 
rated by  a deep  ridge.  Lower  still  there  is  a pair  of  elevations,  also 
with  raised  edges,  and  on  the  ventral  surface  of  the  head  one  or  more 
tubercles.  The  segments  of  the  thorax  are  indistinct;  the  meso thorax 
bears  the  large  raised  ear-shaped  spiracles.  The  abdominal  seg- 
ments are  free  and  about  equal  in  length,  and  have  one  or  more  fringes 
of  hairs  near  their  hind  margins;  the  second  to  the  seventh  segments 
inclusive  have  well  marked  lateral  areas,  covered  with  long  hairs 
which  are  continued  into  the  dorsal  and  ventral  surfaces  and  corre- 
spond to  the  lateral  areas  in  the  larval  integument.  These  hairs  in- 
crease in  length  from  before  backwards,  and  are  best  developed  on  the 
seventh  segment.  The  eighth  segment  is  short,  and  is  provided  with 
six  projecting  spurs  or  teeth,  and  with  a large  anal  tubercle.  In  the 
male  the  tubercle  is  ribbed  and  bounded  anteriorly  by  a continuous 
fringe  of  strong  spines;  in  the  female  the  tubercle  is  smaller  and  the 

4 For  details  concerning  the  structure  of  this  organ,  refer  to  pp.  29-43. 


WERNER  MARCHAND 


25 


fringe  of  spines  is  widely  separated.  The  pupae  of  many  of  the 
larger  species  of  Tabanus  have  in  addition  a lateral  tuft  of  spines  situ- 
ated on  a ridge.  Patton  and  Cragg  were  the  first  to  notice  structural 
differences  in  the  male  and  female  pupae. 

Brauer  (1883)  says  that  he  classifies  the  tabanid  larvae  with  the 
Leptidae  and  Acanthomeridae  (to  which  they  are  undoubtedly  nearly 
related,  as  also  to  the  Asilidae)  under  Homoeodactyla  tanystoma , of 
which  the  larval  characteristics  are: 

Larva  meta-  or  amphipneustic  or  with  tracheal  gills,  usually  with  eyes  at  the 
sides  of  the  head  capsule,  the  latter  usually  hidden  in  the  following  rings,  generally 
more  or- less  retractile,  and  behind  it  eleven  or  twelve  body  segments.  Mandi- 
bles hook-like;  extending  out  of  or  under  them  in  their  concavity  are  the  maxillae, 
which  are  soft-skinned,  and  the  laterally  prominent  maxillary  palpi;  antennae 
short.  Labrum  hooked  or  horn-like,  exserted.  Pupa  a free  “mummy -pupa.” 

Malloch  (1917)  proposes  to  unite  the  Tabanidae  with  the  Leptidae 
to  a superfamily  Tabanoidea,  having  the  following  characteristics: 

11  Larva. — Head  small,  wholly  or  partly  retracted,  permanently  retracted 
portion  with  an  arcuate  dorsal  plate  over  the  longitudinal  rods;  mandibles  strong, 
hook-like,  curved  downward;  maxillae  well  developed,  wholly  or  largely  mem- 
branous, the  palpi  well  developed;  antennae  distinct,  pedunculate.  Body  cy- 
lindrical, with  or  without  pseudopods;  lateral  abdominal  spiracles  absent  in 
Tabanidae,  small,  but  no  lateral  spiracles  distinguishable  in  Leptidae;  apical 
spiracles  in  a vertical  fissure  in  Tabanidae,  exposed  and  separated  in  Leptidae.” 

“ Pupa. — Head  with  strong  cutting  armature;  antennae  with  or  without 
distinct  annuli.  Thoracic  respiratory  organs  sessile.  Wings  and  legs  closely 
fused  to  each  other  and  to  thorax;  fjbre  tarsi  overlying  midpair,  the  latter  over- 
lying  hind  pair,  the  pairs  successively  longer,  hind  pair  not  extending  beyond 
apices  of  wings.  Abdomen  with  seven  pairs  of  lateral  spiracles;  segments  armed 
with  transverse  series  of  slender  bristles  which  become  progressively  stronger 
from  base  to  apex  of  abdomen.” 

Brauer’s  characterization  of  the  Tabanidae  is  the  following: 

Family  Tabanidce. — Larva  usually  metapneustic.  Eyes  distant  from  the  mouth- 
parts,  situated  laterally  and  back  of  the  head  capsule;  the  latter  divided  by  a 
fissure  at  the  inserted  end,  at  the  hind  end  open  and  prolonged  backwards  into 
long  rods,  hidden  in  the  following  segments.  Mandibles  hooked,  often  serrated 
at  the  border;  labrum  forming  a hook-like  projected  septum  between  them. 
Body  eleven-segmented,  often  girdled  with  retractile  fleshy  tubercles  which  are 
often  developed  as  prolegs  at  the  ventral  side  only.  Last  segment  with  a ver- 


26 


THE  EARLY  STAGES  OE  TABANIDiE 


tical  respiratory  fissure,  or  the  last  two  segments  forming  a respiratory  tube. 
Pupa  free,  without  crown  of  hooks  at  the  fore  end,  antennal  sheaths  laterally 
exserted,  parallel  to  the  head.  Between  them  four  swellings  or  ridges,  arranged 
in  a curve  and  formed  by  chitinized  folds.  Above  them  three  tubercles,  forming 
a triangle  (anlage  of  ocelli)  and  behind  them  outwards  two  larger  tubercles. 
Beneath  the  wing  sheaths  on  the  inner  margin  of  the  sheath  of  the  compound 
eyes  on  each  side  are  two  small  tubercles  lying  one  above  the  other.  Anal  seg- 
ment with  six  divergent  cone-shaped  pointed  hooks.  Spiracles  behind  the  head 
and  on  the  seven  abdominal  segments  distinct  and  large,  the  former  with  kid- 
ney-shaped or  ear-shaped  margin  ( Therioplectes ) and  often  very  large.  The 
pupa  rests  in  the  ground  or,  in  some  species  {Therioplectes) , remains  in  the  water. 

Malloch  describes  the  body  of  the  larvae  as  “circular  in  transverse 
section,  elongate,  tapering  at  both  ends,  and  with  encircling  loco- 
motor swellings  at  the  segmental  sutures  in  all  genera  except  GoniopsP 

Malloch’s  description  of  the  tabanid  pupa,  based  on  the  study 
of  a number  of  species,  is  the  following: 

\ 

11  Pupa. — Head  without  projecting  thorns.  Thoracic  respiratory  organs  ses- 
sile, connected  subcutaneously  with  a large  cavity  on  each  side  of  median  line 
close  to  anterior  margin  of  prothorax.  [Plate  13,  Figs.  153  and  154.]  Wings 
and  legs  rather  short.  Abdominal  armature  consisting  of  1,  or  2 closely  con- 
tiguous, series  of  bristles  on  each  dorsal  segment  except  first,  and  a weaker  trans- 
verse series  on  ventral  segments;  apical  segment  ending  in  six  stout  processes 
which  are  more  or  less  radiate  and  pointed.  [Plate  13,  Figs.  162  and  163.]” 

On  the  habits  of  the  larvae  before  pupation,  facts  have  been  pub- 
lished by  Neave  (1915). 

Before  the  larvae  have  reached  their  full  growth,  which  in  many 
cases  signifies  the  beginning  of  a resting  period,  they  usually  lie 
buried  in  the  mud,  head  downwards,  with  their  syphons  projecting 
immediately  above  the  surface  of  the  mud  or  of  a shallow  layer  of 
water  above  it  if  it  is  present.  In  the  resting  stage  the  syphons  do 
not  seem  to  be  used  and  the  larvae  remain  several  inches  below  the 
surface  for  weeks  or  even  months.  This  is  presumably  an  adapta- 
tion connected  with  a climate  in  which  there  is  a very  marked  dry 
season,  and,  consequently,  a risk  of  the  mud  in  which  they  are  lying 
more  or  less  drying  up.  Pupation  appears  to  take  place  in  normal 
circumstances  an  inch  or  more  below  the  surface,  though  occasion- 
ally in  captivity  individuals  pupated  lying  horizontally  upon  it. 
The  pupa  is  normally  upright  in  the  mud,  and  after  pupation,  as  soon 


WERNER  MARCHAND 


27 


as  the  case  has  hardened,  it  works  its  way  up  by  means  of  its  rings 
of  spines  and  the  aster  (a  name  proposed  for  the  terminal  whorl  of 
spines),  until  the  pupal  head  lies  just  below  the  surface,  being  often 
visible  from  above.  The  pupa  at  first  is  usually  of  a pale  yellowish 
or  greenish  color,  but  darkens  as  the  imago  develops  within,  the 
process  beginning  with  the  eyes. 

Neave  observed  that  in  normally  fine  weather  the  imagos  of  all 
species  almost  invariably  emerged  between  noon  and  3 p.m.  They 
were  more  irregular  during  spells  of  dull  and  rainy  weather.  The 
process  of  emergence  seems  to  be  similar  in  individuals  of  all  genera, 
whether  Chrysops,  Hcematopota , or  Tabanus.  The  head  of  the  pupa 
splits  in  the  median  dorsal  line  and  the  imago  rapidly  emerges  until 
only  the  end  of  the  abdomen,  which  is  at  first  enormously  elongated, 
remains  in  the  pupa  case.  The  wings  at  this  stage  are  milky  white 
and  the  darker  markings,  if  any,  are  barely  visible.  The  imago 
usually  remains  in  this  position  for  two  or  three  minutes  before 
completely  leaving  the  pupa  case.  It  is  capable  of  flight  very  soon 
after  this,  but  if  undisturbed  sits  for  about  half  an  hour  on  any 
suitable  object  near  by  while  the  wings  dry  and  assume  their  normal 
coloration,  and  the  abdomen  its  normal  shape.  During  this  period 
several  drops  of  a milky  white  fluid  (the  meconium)  are  passed 
through  the  anus. 

Bionomics. 

On  the  bionomics  of  the  tabanids  in  the  early  stages  we  possess 
many  interesting  notes  by  Neave  (1915).  From  the  results  of  a 
year’s  collection  of  adults  in  one  locality,  and  from  other  evidence, 
it  is  probable  that  the  majority  of  tabanids,  at  least  of  Nyasaland, 
have  only  one  brood  a year.  This  is  certainly  true  of  nearly  all  the 
species  of  Tabanus  and  of  Dorcalcemus  fodiens  Aust.  It  is  possible, 
however,  that  certain  species  of  Chrysops  and  Hcematopota  may  be 
double-brooded;  much  doubtless  depends  on  the  larval  food  supply, 
climate,  etc. 

According  to  Neave,  in  the  case  of  many  species  the  larva  grows 
very  slowly  after  hatching  and  often  takes  six  months  or  more  to 
become  full  grown.  It  then,  especially  in  species  of  Tabanus , goes 
through  a resting  period,  during  which  it  remains  buried  in  mud  or 
sand,  sometimes  at  a considerable  depth.  In  contrast  to  the  lengthy 


28 


THE  EARLY  STAGES  OF  TABANIDiE 


larval  stage,  the  pupal  period  is  short,  varying,  in  Neave’s  experience, 
from  10  to  16  or  18  days,  according  to  the  species  and  the  climatic 
conditions,  the  longer  period  being  usual  for  the  larger  species  of 
Tabanus. 

One  difficulty  connected  with  the  question  of  these  flies  having 
more  than  one  brood  a year  arises  from  the  fact  that  even  in  larvae 
from  the  same  batch  of  eggs  the  rate  of  growth  is  extremely  variable, 
and  consequently  the  processes  of  pupation  and  emergence  do  not  take 
place  simultaneously  in  a certain  proportion  of  the  individuals.  Some 
of  the  remainder  take  longer  to  reach  maturity,  others  seem  to  pass 
through  an  extended  dormant  period.  The  adults  arising  from  these 
emerge  at  irregular  intervals,  often  months  later.  This  probably 
explains  the  capture  of  odd  specimens  of  any  species  long  after  the 
usual  season.  It  would  also  seem  not  improbable  that  individuals 
which  miss  their  normal  season  for  pupation  in  some  circumstances 
continue  in  the  larval  stage  until  the  following  year.  Thus  Neave 
possessed  in  his  laboratory  in  January  and  February  examples  of 
larvae  of  Tabanus  corax , some  still  in  a dormant  state  and  others  not 
yet  mature,  the  season  for  the  adult  flies  being  over  by  the  begin- 
ning of  January.  It  would  appear  that  these  would  not  have  pro- 
duced imagos  until  the  following  December,  though  Neave  was  un- 
able to  decide  this  point  on  account  of  his  return  from  Nyasaland  to 
England.  Hine  states  that  the  larvae  of  Tabanus  stygius — probably — 
hibernate  twice  before  giving  the  adult. 

Surcouf  and  Ricardo,  however,  assert  that  in  spite  of  the  opinions 
to  the  contrary  the  tabanids  seem  to  have,  at  least  in  Algiers,  often 
two  generations  in  a year.  These  authors  have  taken  from  a horse 
several  fresh  specimens  in  May  (1908),  while  the  same  species  is  taken 
in  France  and  Algiers  in  the  fall.  Maxwell-Leffroy  and  Howlett  state 
that  at  Pusa  (Bengal)  there  are  apparently  three  broods  of  Tabanus 
yearly,  flies  emerging  at  the  beginning  and  end  of  the  hot  weather 
(about  February  and  June)  and  at  the  end  of  the  rains  (October). 
These  statements  should  be  compared  with  those  made  by  Neave. 
Hibernation  takes  place  in  the  larval  state  in  India  in  all  species 
which  were  observed  by  Maxwell-Leffroy  and  Howlett;  and  the  same 
holds  good  for  all  known  American  species  (Hine),  larvae  being  found 
late  in  the  fall  and  again  in  early  spring.  No  pupae  have  been  found 
in  the  winter. 


WERNER  MARCHAND 


29 


Special  Anatomy  oj  Tabanid  Larva.  Graber’ s Organ. 

Almost  the  only  detail  of  the  structure  of  tabanid  larvae  which  has 
been  studied  more  extensively  is  a peculiar  organ  situated  on  the 
dorsal  side  of  the  segment  before  the  last,  and  discovered  first  by 
Graber  (1878),  who,  while  conceding  that  it  has  very  little  resem- 
blance to  an  auditory  organ,  nevertheless  may  have  to  be  placed  in 
this  category.  As  the  situation  of  the  organ  is  rather  unusual  if  it  is 
auditory,  Graber  recalls  the  discovery  by  Grobben  of  similarly  situ- 
ated organs  in  the  larva  of  another  fly,  Ptychoptera  contaminata 
(Tipulidae),  and  of  which  the  auditory  function  seems  fairly  certain. 
Whether  similar  organs  are  found  in  other  dipterous  larvae  is  not 
known;  Malloch  (1917)  does  not  mention  them.  The  organs  seem  to 
occur  in  all  tabanid  larvae,  but  to  be  more  easily  seen  in  the  young 
stages;  they  have  been  overlooked  by  some  later  investigators,  nota- 
bly Hart  (1895)  and  Hine  (1901-06),  but  have  been  seen  and  figured 
by  Walton  (1908)  for  Goniops  ckrysocoma  (only  as  dots),  and  by 
Mitzmain  (1913)  for  Tabanus  striatus,  all  of  whom  have  apparently 
overlooked  the  European  literature  on  the  subject,  Mitzmain  assum- 
ing that  the  organ  must  either  be  peculiar  to  the  larvae  observed 
by  him,  or  have  been  overlooked  by  the  previous  authors. 

Graber  found  the  organs  in  the  abdomen  of  the  larva,  at  the 
sides  of  the  two  last  segments.  They  consist  of  a cornea-like  infla- 
tion of  the  integument  which  is  covered  inside  with  its  epithelium. 
The  open  inner  side  of  this  vesicular  invagination  seems  to  be  closed 
by  a membrane  supported  by  radial  elastic  fibers,  the  fundus  of  which 
can  be  extended  by  means  of  a strong  muscle.  According  to  Graber, 
the  presence  of  a special  nerve,  which,  however,  approaches  the 
vesicle  without  any  specialized  termination,  is  proof  that  we  are 
dealing  with  a sense  organ. 

However,  what  characterizes  them  as  auditory  organs  are  two  or 
three  otolith-like  bodies  found  in  the  liquid  contents  of  the  capsule. 
These  abdominal  otocysts  consequently  differ  from  antennal  structures 
described  elsewhere  by  Graber,  first,  by  belonging  to  the  integument 
itself,  second,  by  their  inner  wall  not  being  formed  by  chitin  but  by 
the  epithelium.  As  a consequence  of  this,  the  development  of  cuticu- 
lar  auditory  hairs  is  naturally  also  suppressed,  and  a new  type  of 


30 


THE  EARLY  STAGES  OF  TABANID^E 


auditory  capsules  is  developed,  which  Graber  distinguishes  as  oto- 
cysts  without  cilia  (aciliate)  from  other  known  otocysts  (ciliate 
otocysts) . 

The  organs  were  found  by  Graber  (Spring,  1878)  on  a dipterous 
larva  collected  with  other  material,  on  the  bottom  of  a mud  pond 
in  a brick  factory.  The  larva  (Plate  9,  Fig.  103)  was  when  extended 
about  40  mm.  long,  cylindric,  strongly  spindle-shaped,  and  pointed 
at  the  end,  and  except  the  dark  intestinal  system,  of  an  almost  glassy 
transparence.  Eleven  segments  were  counted,  which  with  the  ex- 
ception of  the  terminal  ones,  were  surrounded  by  a girdle  of  papilli- 
form retractile  processes.  Unfortunately,  as  literature  was  not  acces- 
sible, the  species  could  not  be  determined. 

In  order  to  see  the  organ  in  the  fresh  condition,  the  larva  is  laid 
on  its  ventral  side  and  fastened  with  an  elastic  holder.  The  organ 
(Plate  9,  Figs.  104  to  108)  lies  in  the  median  line  of  the  dorsal  side, 
behind  the  termination  of  the  dorsal  blood  vessel,  and  immediately 
behind  the  border  incision  between  the  ninth  and  tenth  segments. 
By  focusing  from  above,  at  first  the  body  cuticle  becomes  visible, 
which  derives  from  the  presence  of  longitudinal  ridges  the  extra- 
ordinary elasticity  characteristic  of  these  larvae.  When  focusing 
farther  down,  the  epithelium  is  seen,  consisting  of  flat  polyhedric 
cells,  and  following  this  a network  of  pale  lobes  and  trabeculae  with 
dendritic  tracheal  expansion;  namely,  the  fat  body.  Immediately 
underneath  these  tissues  lies  the  organ  in  question,  which  is  conse- 
quently completely  separated  from  the  integument.  It  consists  of 
a pale  capsule  0.3  mm.  in  length  and  pear-shaped,  its  free  and  broader 
end  directed  upwards,  while  its  pointed  hind  end  is  prolonged  into  a 
narrow  tube.  The  capsule  being  of  considerable  size  is  visible  even 
at  slight  magnification.  Moreover,  it  is  not  likely  to  be  overlooked 
because  of  the  intensely  black  bodies  included  in  it,  which  strongly 
contrast  with  the  light  background. 

In  detail  the  structure  of  the  organ  appears  to  be  peculiar.  From 
the  capsule  proper  with  its  tube  the  nerves  and  muscles  attached  to  its 
anterior  end  may  be  distinguished.  The  whole  capsule  together  with 
the  terminal  tube  appears,  as  Graber  says,  to  be  a cecum-like  in- 
vagination of  the  ectoderm.  Unfortunately  the  origin  of  the  ter- 
minal tube  could  not  be  found  by  Graber;  it  apparently  lies  in  the 


WERNER  MARCHAND 


31 


last  body  segment  and  is  in  no  way  connected  with  the  intestine, 
which  terminates  at  the  end  of  the  segment  before  the  last,  or  with 
the  sexual  organs.  In  Graber’s  account  it  remains  questionable 
whether  the  terminal  tube,  as  was  supposed,  really  originates  in  the 
integument.  The  tube  and  the  capsule  forming  its  enlarged  terminal 
part  behave  histologically  like  a glandular  formation.  The  main  layer 
is  an  epithelium  consisting  of  large  cells.  This  is  seen  best,  especially 
after  treatment  with  35  per  cent  potassium  hydroxide,  at  the  distal 
(head)  end  of  the  capsule.  The  cells  appear  as  elongated,  sac-like, 
pale  compartments,  separated  from  one  another  by  bridge-like  septa, 
always  showing  a dark  nucleus  accompanied  by  a small  nucleolus. 
In  the  remaining  part  no  distinct  cell  borders  can  be  distinguished, 
but  only  large  granulated  nuclei.  In  the  terminal  tube  the  latter  are 
arranged  alternating  behind  one  another,  similarly  as  in  the  narrow 
secretory  ducts  of  true  glands.  The  epithelial  tube  is  covered  at  the 
outside  by  a thin  homogeneous  covering  which  may  be  considered  as 
a tunica  propria. 

The  structures  belonging  to  the  third  stratum,  that  is,  to  the 
chitinous  membrane,  are  peculiar.  Leaving  aside  certain  complica- 
tions, we  find  first  a chitinous  capsule  corresponding  to  the  epithelial 
one,  which  is  prolonged  into  a narrow  canal  corresponding  to  the 
terminal  tube.  This  canal  pursues,  inside  the  terminal  tube,  an  un- 
dulating course,  curved  alternately  to  the  right  and  left,  suggesting 
the  muscle  in  the  stem  of  a Vorticella. 

The  chitinous  capsule  enclosed  within  the  epithelial  vesicle  is 
often  very  thin  and  delicate  compared  with  the  thickness  of  its 
matrix,  and  is  perfectly  transparent.  Its  free  (inner)  surface,  how- 
ever, shows  at  high  magnification  small  tegula-like  overlapping 
scales.  In  this  chitinous  capsule  the  black  bodies  already  mentioned 
are  enclosed. 

At  low  magnification  these  bodies  appear  as  simple  homogeneous 
globules.  At  the  highest  magnification,  however  (Plate  9,  Fig.  107), 
they  are  found  to  be  hollow  chitinous  structures  with  a somewhat 
wrinkled  surface,  which  after  the  fashion  of  a volumetric  flask  are 
prolonged  into  a narrow  hollow  stem  or  peduncle.  The  bodies  re- 
main perfectly  black  and  opaque  even  when  boiled  in  caustic  potash; 
consequently  they  seem  to  have  very  thick  and  strong  chitinous 


32 


THE  EARLY  STAGES  OF  TABANIDiE 


walls.  Sometimes  it  seems  as  if  they  are  filled  with  a dark  tough 
substance,  projecting  in  the  shape  of  a papilla  or  of  a granulated 
string  into  the  lumen  of  the  peduncle.  Eight  of  these  pedunculate 
bodies,  as  Graber  calls  them,  were  present  in  the  larva  examined, 
arranged  in  four  pairs,  lying  one  behind  the  other,  giving  to  the 
vesicle  the  appearance  of  an  internally  segmented  organ.  The 
bodies  of  the  first  two  pairs  are  of  about  the  same  size,  30  ju  in  di- 
ameter, the  length  of  the  peduncle  26  n,  its  width  at  the  tip  1.8  fi. 
The  bodies  of  the  two  following  pairs  immediately  touching  one 
another  are  considerably  smaller  than  the  rest,  their  diameter  being 
only  20  ju. 

The  compound  nature  of  the  organ  appears  more  distinctly  than  in 
the  serial  arrangement  of  the  pedunculate  bodies,  in  the  repetition  of 
the  covers  in  which  they  are  enclosed.  There  are  not  four  such  covers 
or  secondary  sacs,  however,  but  only  three,  as  the  two  posterior  pairs 
of  pedunculate  bodies  are  contained  in  a common  envelope.  The 
first  sac  is  formed  by  the  capsule  itself;  that  is,  by  its  rounded  (head) 
end.  The  pedunculate  bodies  are  observed  hanging  by  their  pedicel 
from  the  slightly  invaginated  upper  wall,  and,  like  the  following  ones, 
turned  from  the  inside  towards  the  outside  in  a somewhat  oblique 
direction.  The  space  in  which  the  bodies  are  found,  however,  is 
separated  also  from  the  remaining  lumen  of  the  capsule,  and,  as  far 
as  could  be  seen,  by  a transverse  septum  issuing  from  the  side  walls. 

The  second  pair  of  pedunculate  bodies  is,  however,  surrounded  by 
an  independent  sac  entirely  separated  from  the  main  capsule,  the 
fixation  of  the  pedunculate  bodies  themselves  at  the  inner  upper  wall 
of  the  secondary  vesicle  being  exactly  the  same  as  that  in  the  first 
capsule.  This  second  sac,  however,  is  not  completely  closed  behind 
the  pedunculate  bodies,  but  is  forming  here  only  a neck-like  con- 
traction, its  walls  otherwise  being  continued  into  the  following  sac. 

The  third  inner  sac  resembles  the  second  one  in  all  essentials,  but 
encloses,  as  already  mentioned,  two  pairs  of  pedunculate  bodies, 
which  again,  in  a manner  analogous  to  that  in  the  former  cases,  are 
inserted  into  its  walls. 

Probably  the  last  two  sacs  are  evaginations  of  the  fundus  of  the 
common  capsule,  fitted  into  one  another  like  the  sheaths  of  an  onion. 
In  this  way  the  first  pair  is  surrounded  by  one  envelope,  the  second 


WERNER  MARCHAND 


33 


by  two,  and  the  third  and  fourth  by  four  envelopes.  The  accessory 
parts  of  the  organ  have  also  been  studied  by  Graber. 

At  a moderate  magnification  it  is  possible  to  discern,  in  addition 
to  the  tube  extending  backwards  from  the  capsule,  two  other  liga- 
ments originating  at  the  sides  of  the  pear-shaped  part,  so  that  the 
whole  organ  appears  to  be  held  in  place  by  three  ligaments,  one  of 
which  is  the  terminal  tube.  The  two  lateral  ligaments  extend  ob- 
liquely, crossing  the  two  large  tracheal  trunks,  in  a forward  and  out- 
wards direction,  inserted  in  a place  not  determined  by  Graber  but 
probably  lying  in  the  seventh  segment.  At  higher  magnification  the 
anterior  ligaments  are  found  to  be  muscles,  and  immediately  behind 
the  place  of  origin  of  these  muscles  two  pairs  of  nerves  are  seen  at- 
tached to  the  capsule.  The  first  nerve  being  rather  thin  forms  imme- 
diately at  the  head  of  the  capsule  a thick  ganglion-like  swelling,  in 
which  several  pale  nuclei  are  discernible.  The  character  of  the  end- 
ing of  this  nerve  has  not  been  determined;  Graber  assumes  that  it 
enters  into  connection  with  the  capsular  epithelium.  Nothing  more 
is  known  about  the  termination  of  the  second  nerve  which  is  much 
thicker  than  the  first  one. 

All  the  parts  described,  the  capsule,  the  terminal  tube,  the  muscles, 
and  nerves  are  connected  with  one  another  and  with  the  surrounding 
organs,  as  also  with  the  tracheae  and  with  the  band-like  extensions 
of  the  heart  muscles,  by  a peculiar  connective  tissue.  The  latter 
shows  the  greatest  affinity  with  certain  elastic  reticulate  tissues  of 
higher  animals.  These  tissues  play  a part,  according  to  Graber,  in 
the  extraordinary  changes  in  the  relative  situation  of  the  parts 
during  the  movements  of  the  larvae.  Graber  discusses  the  possible 
function  of  the  organ  he  described,  assuming  that  it  must  be  either  a 
gland  or  sense  organ.  The  presence  of  a duct  leading  to  the  exte- 
rior seems  to  indicate  the  former,  but  the  arrangement  of  the  con- 
tents seems  to  contradict  this  view. 

If  the  organ  is  considered  a gland,  this  would  imply  that  a secretion 
formed  by  the  epithelial  cells  is  discharged  into  the  chitinous  capsule. 
In  this  case,  however,  no  explanation  is  found  for  the  presence  of  the 
pedunculate  bodies,  not  to  mention  the  various  interior  secondary 
capsules.  The  pedunculate  bodies  have  no  free  opening,  and  while 
they  are  hollow  and  possibly  have  been  formed  by  invagination  of 


34 


THE  EARLY  STAGES  OF  TABANHD^E 


the  walls  of  the  capsule,  the  place  of  invagination  seems  to  have 
disappeared. 

Graber  therefore  decided  that  the  organ  must  be  a sense  organ, 
which,  however,  according  to  its  peculiar  structure  and  position  can- 
not be  either  an  organ  of  touch,  smell,  taste,  or  sight,  and  is  conse- 
quently placed  among  the  auditory  organs.  Graber  also  believed 
that  he  found  the  two  main  features  of  a cystoid  auditory  organ, 
namely  a cyst-like  cell  system,  connected  with  a nerve,  and  an  in- 
ternal fluid  medium  which  may  carry  the  sound.  There  were  lacking 
only  the  characteristic  elastic  appendages  of  the  auditory  cells. 

Graber  assumes  that  under  certain  conditions  the  auditory  cells 
may  be  stimulated  by  waves  of  sound  even  in  the  absence  of  special 
end  organs,  in  the  same  way  that  the  light-perceiving  elements  of  the 
eye  in  part  are  also  affected  by  light-waves  in  the  absence  of  special 
terminal  organs  as  found  in  highly  developed  organs  of  sight. 

The  presence  of  the  peculiar  pedunculate  bodies  seems,  more  than 
anything  else,  to  have  determined  Graber’s  view,  in  as  far  as  they 
form  a good  analogy  to  the  otoliths  commonly  found  in  auditory  or- 
gans of  the  cyst-like  type.  The  pedunculate  bodies  are  comparatively 
heavy,  thick-walled  bodies  and  are  attached  to  the  cysts  by  means  of 
thin  and  probably  elastic  filaments  or  strings;  they  may  be  compared 
with  the  clappers  of  a bell,  which  facilitate  their  function  as  otoliths. 

Graber  classifies  all  auditory  organs  occurring  among  insects,  as 
(1)  elementary  organs,  consisting  of  isolated  hearing  cells  or  auditory 
hairs,  (2)  cystoid  auditory  organs,  gymnotocysts,  and  chitinotocysts, 
found  in  crustaceans  and  many  insects,  and  (3)  tympanal  organs,  pro- 
vided with  auditory  rods  as  found  in  Orthoptera.  The  chordo tonal 
organs  are  related  to  the  latter  and  differ  by  the  absence  of  a tympanal 
membrane.  The  organ  in  question  is  classified  among  the  cystoid 
organs. 

Henneguy  found  the  same  organs  in  small  larvae  resembling  larvae 
of  Stratiomys  (Lecaillon),  (Plate  10,  Fig.  109),  which  undoubtedly 
belong  to  Tabanus.  The  organ  in  this  instance  (Plate  10,  Fig.  110) 
is  different.  It  comprises  a cellular  mass  situated  in  front  of  the 
organ  and  evidently  connected  with  the  dorsal  vessel,  a capsule  fol- 
lowing it,  containing  two  pigmented  bodies  arranged  as  described  by 
Graber,  and,  finally,  a cyst  prolonged  backwards  into  a filament  but 


WERNER  MARCHAND 


35 


not  containing  pigmented  bodies.  Henneguy  is  inclined  to  place  the 
organ  among  the  chordotonal  organs. 

Lecaillon,  having  in  1904  sent  some  larvae  of  Tabanus  quatuorno- 
tatus  to  Henneguy,  studied  the  organ  at  the  latter’s  suggestion.  He 
records  a number  of  facts  which  may  facilitate  further  research  on 
the  subject.  The  principal  results  of  his  observations  are  as  follows: 

1.  Graber’s  organ  exists  in  all  larvae  of  T alarms  quatuornotatus.  It  should 
consequently  be  sought  for  among  the  tabanids,  and  possibly  also  in  related 
families. 

2.  It  already  exists  in  the  larvae  hatching  from  eggs,  but  it  continues  to  de- 
velop as  the  larvae  grow. 

3.  In  very  young  larvae  its  structure  corresponds  to  that  described  by  Henne- 
guy; in  fact  he  made  his  observations  on  very  young  larvae. 

4.  As  the  larvae  grow,  the  primitive  structure  becomes  more  complicated  and 
more  closely  resembles  the  structure  described  by  Graber.  This  author  ob- 
served full  grown  larvae. 

5.  Consequently  it  can  be  stated  that  Henneguy ’s  description  applies  to  the 
young  condition  of  the  organ,  and  that  of  Graber  to  the  fully  developed  condition. 

6.  In  Lecaillon’s  observations,  as  shown  by  the  figures,  the  pigmented  bodies 
do  not  always  remain  regularly  arranged  in  pairs,  contrary  to  Graber’s  descrip- 
tion. They  are  seen  frequently  placed  one  behind  the  other  in  the  posterior  duct 
of  the  organs.  Sometimes  there  is  an  odd  number  of  them  in  this  duct,  which 
means  undoubtedly  that  these  granules  can  sometimes  be  discharged  or  expelled. 

7.  While  nothing  can  be  said  with  certainty  about  the  function  of  Graber’s 
organ,  Lecaillon  considers  it  glandular  in  nature  rather  than  a sense  organ. 

The  figure  of  the  larva  given  by  Lecaillon  (Plate  10,  Fig.  117)  was 
obtained  from  a living  larva  of  Tabanus  quatuornotatus  one  month 
old,  seen  in  dorsal  aspect  with  light  falling  through,  a larva  at  this 
stage  being  still  very  small.  Two  other  figures  (Plate  10,  Figs.  118 
and  119)  give  the  aboral  extremity  of  two  other  larvae  slightly  older 
than  the  first  one. 

As  seen  in  these  figures,  the  main  part  of  the  organ  of  Graber  oc- 
cupies the  median  and  dorsal  region  of  the  next  to  the  last  segment,  in 
almost  its  entire  length,  and  is  situated  not  far  from  the  two  large 
tracheal  trunks,  which  open,  one  near  the  other,  at  the  end  of  the  last 
abdominal  segment.  It  consists  mainly  of  an  oval  sac  or  cyst  pro- 
longed posteriorly  into  a tube.  The  oval  and  dilated  part  is  subdi- 
vided by  a septum  in  two  cysts  placed  one  behind  the  other.  Careful 


36 


THE  EARLY  STAGES  OF  TABANID^E 


study  of  this  region  shows  that  the  two  cysts  are  not  completely  sepa- 
rated and,  on  the  contrary,  communicate  with  one  another  in  their 
axial  region;  in  other  words,  the  septum  which  separates  them  is 
incomplete.  The  tubular  region  which  prolongs  the  posterior  cyst 
begins  towards  the  middle  of  the  segment  next  to  the  last  and  opens 
in  the  median  line  not  far  from  the  openings  of  the  two  tracheal  tubes. 
This  tubular  region  is,  consequently,  about  as  long  as  the  dilated  por- 
tion of  the  organ.  The  fundus  of  the  sac,  that  is  its  anterior  region, 
has  thicker  walls  than  any  other  part.  There  is  in  this  region  a 
cellular  mass  similar  to  that  described  by  Henneguy  in  the  organ  of 
the  undetermined  larva  which  he  examined. 

The  ink-black  bodies  can  be  found,  according  to  Lecaillon,  in  both 
capsules  and  in  the  tubular  portion.  The  first  capsule  always  con- 
tains two  which  are  situated  anteriorly,  one  to  the  right,  the  other  to 
the  left  of  the  median  line.  By  carefully  examining  their  arrangement 
it  is  found  that  they  are  attached  to  the  cellular  mass  at  the  fundus 
of  the  cyst,  each  by  a small  pedicel,  as  has  been  described  by  Graber 
and  by  Henneguy,  whose  observations  are  confirmed  by  Lecaillon. 
These  pedicels  do  not  show  on  Lecaillon’ s figures,  which,  as  he  says, 
were  drawn  from  living  larvae  under  conditions  when  the  details  were 
not  clearly  visible.5  The  second  capsule  contains  sometimes  also  two 
of  the  black  bodies,  arranged  as  in  the  first  capsule,  but  often  it 
does  not  contain  any  of  them. 

The  tubular  region  often  contains  no  black  bodies.  But  frequently 
and  especially  in  older  larvae,  it  almost  always  contains  a varying 
number.  The  maximum  number  which  Lecaillon  found  was  six,  but 
there  may  be  only  five,  four,  three,  or  two,  even  in  larvae  of  the  same 
age  and  living  under  the  same  conditions.  As  the  caliber  of  the  tubu- 
lar region  is  narrow,  the  black  globules  are  placed  here  in  a length- 
wise row,  and  not  in  pairs  placed  transversely,  as  in  the  capsules. 

As  Lecaillon  wished  to  ascertain  whether  the  black  bodies  could 
eventually  be  expelled  to  the  exterior,  a larva  which  had  six  globules 
in  the  tubular  portion  of  the  organ  was  placed  under  observation. 
Eight  days  afterwards  Lecaillon  found  that  the  tube  contained  only 

5 1 found  that  living  tabanid  larvae  up  to  15  mm.  in  size  can  be  examined  by 
means  of  a compound  microscope,  without  suffering  injury  from  the  pressure 
necessary  to  hold  them  in  place. 


WERNER  MARCHAND 


37 


two  globules,  four  evidently  having  been  expelled.  At  about  the  same 
time  another  larva  of  the  same  age  was  found  to  contain  only  the 
two  bodies  of  anterior  cyst;  all  the  others  had  been  thrown  out.6 
In  summarizing  Lecaillon  states: 

(1)  The  black  bodies  are  formed  by  the  cellular  mass  which  constitutes  the 
fundus  of  the  capsule.  (2)  The  globules  are  detached  periodically  to  be  expelled 
to  the  exterior  after  a longer  or  shorter  time.  (3)  They  are  regenerated  at  the 
bottom  of  the  cyst  when  the  others  have  been  expelled. 

These  conclusions  of  Lecaillon  appear  only  partly  warranted. 
From  observations  made  hitherto  there  is  no  indication  of  a relation 
of  the  discharge  of  these  bodies  and  their  new  formation. 

Concerning  the  nature  of  the  black  bodies,  Lecaillon  states  that  they 
are  not  hard  as  if  they  were  mineral  granulations;  they  are  not  affected 
by  reagents,  as  acid  fixation  fluids;  they  may  be  cut  when  the  organ  is 
sectioned.  Consequently  they  seem  to  be  a pigmented  material, 
excreted  by  the  cellular  mass  which  forms  the  bottom  of  the  cyst. 
Lecaillon  alludes,  in  suppport  of  this  view,  to  the  fact  that  the  larvae 
of  Tabanus  quatuornotatus  have  a completely  white  body  though  the 
substances  found  in  the  digestive  tract  (organic  relics)  are  usually 
blackish.  The  pigment  derived  from  the  alimentary  substances,  or 
formed  normally  in  the  body,  might  be  excreted  by  means  of  this 
particular  gland. 

Paoli  in  Florence  in  1907  studied  the  same  organ  in  various  taba- 
nid  larvae  which,  on  the  authority  of  Bezzi,  are  said  to  belong  prob- 
ably to  Tabanus  cordiger  Meig.  or  Tabanus  autumnalis  L.  Paoli, 
however,  asserts  that  in  all  probability  many  species  of  this  family 
possess  Graber’s  organ  more  or  less  developed  and  also  with  slight 
modifications  in  details  of  structure,  according  to  age  and  species. 
For  the  description  of  the  larvae  studied  by  Paoli  see  pages  91-93, 
Tabanus  autumnalis. 

According  to  Paoli’ s description,  Graber’s  organ  is  found  in  the  vis- 
ceral cavity,  situated  dorsally  under  the  subcutaneous  muscular  strata, 
in  the  anterior  third  of  the  eighth  abdominal  segment  between  the 
two  large  tracheae  (Plate  10,  Figs.  115  and  116).  It  is  a little  pear- 

6 1 have  been  able  to  confirm  Lecaillon’s  observations  in  the  larvae  of  Tabanus 
atratus  (1916). 


38 


THE  EARLY  STAGES  OF  TABANIDiE 


shaped  cyst  with  a slight  constriction  in  its  wider  part;  its  pointed 
end  is  turned  hindwards.  Inside  this  cyst  are  found,  in  the  cases 
examined,  several  pairs  of  black  rounded  chitinous  pedunculate 
bodies;  each  pair  of  these  bodies  is  in  turn  enclosed  in  a special  chit- 
inous capsule  filled  with  liquid.  The  attachment  of  the  muscles  and 
nerves  to  this  cyst  are  described  in  detail.  The  cyst  is  continued, 
at  its  pointed  end,  into  a contorted  canal  which  opens  in  the  deepest 
place  of  the  infolding  between  the  eighth  and  ninth  abdominal  seg- 
ments (Plate  10,  Fig.  115).  The  canal  and  the  cyst  are  covered  in- 
side with  chitin  and  completely  surrounded  by  the  hypoderma,  so  as 
to  warrant  the  conclusion  that  the  whole  organ  must  be  an  invagina- 
tion of  the  integument,  as  Graber  had  supposed,  though  he  was 
unable  to  see  the  opening  of  the  terminal  tube. 

According  to  Graber,  the  first  cyst  contains  in  its  interior  four  pairs 
of  pedunculate  chitinized  bodies;  the  first  pair  being  in  a closed  cap- 
sule, the  second  inside  another  capsule,  the  latter  not  completely 
closed  posteriorly,  and  finally  the  remaining  two  pairs  contained  in  a 
common  sac,  open  posteriorly. 

Paoli  states  that  the  number  of  pedunculate  bodies  is  not  limited 
to  four  pairs,  but  varies  according  to  the  age  of  the  larva.  Graber  also 
said  (in  his  later  work),  that  in  the  young  larva  there  is  only  one 
pair  of  such  pedunculate  bodies,  and  that  the  second  pair  is  formed 
later.  Henneguy,  who  examined  a newly  hatched  larva,  found  only 
one  pair. 

Paoli  found  four  pairs  in  larvae  about  1 cm.  in  length,  but  in  speci- 
mens of  larvae  in  later  stages  of  development  he  always  found  a greater 
number,  up  to  seven  pairs  in  larvae  of  almost  3 cm.  in  length.  Each 
pair  was  found  enclosed  in  a capsule  which  remains  more  or  less  open 
posteriorly,  but  which  is  always  present;  the  largest  of  them,  that  is, 
that  which  is  located  anteriorly,  has  the  thickest  walls  and  is  formed 
last,  and  it  is  only  this  one  which  is  really  living  and  in  function, 
while  all  the  others  are  dead  and  have  no  function  whatever,  differing 
little  from  one  another,  especially  the  capsules  enclosing  the  smallest; 
namely,  the  oldest  pairs  of  pedunculate  bodies. 

Each  of  the  pedunculate  bodies  has  the  shape  of  a slightly  elliptic 
ball,  their  surface  being  smooth  or  sometimes  rugose.  They  are 
strongly  chitinized,  black,  frail,  and  breakable,  as  under  pressure 


WERNER  MARCHAND 


39 


they  may  be  reduced  to  small  fragments;  the  pedicel  is  inserted  ob- 
liquely, equal  to  the  latter  in  length.  The  pedicel  itself  is  chitinous 
but  not  black;  at  most  it  is  brown  in  the  neighborhood  of  its  inser- 
tion in  the  globule;  at  the  other  end  it  has  a widening  by  means  of 
which  it  fastens  itself  in  a little  cavity  of  the  wall  of  the  chitinous 
capsule.  The  pairs  of  pedunculate  bodies  are  attached  each  one 
to  the  central  portion  of  the  anterior  wall  of  the  capsule  itself,  and  the 
pedicels  are  a little  divergent  so  that  the  two  spherical  bodies  are 
located  a certain  distance  from  one  another,  suspended  in  the  liquid 
which  fills  the  cavity  of  the  capsule.  The  pedunculate  bodies  are  of 
dimensions  increasing  in  the  direction  of  the  head;  in  a larva  with 
four  pairs  these  bodies  measured  for  each  pair  11,  15,  16.5,  and  18  n 
in  diameter. 

Paoli  explains  the  probable  manner  in  which  these  cysts  and  the 
tube  are  formed.  It  has  been  stated  that  the  latter  opens  into  the 
innermost  part  of  the  sulcus  which  limits  the  eighth  abdominal  seg- 
ment from  the  ninth;  Graber  did  not  see  this  opening  but  supposed 
that  it  was  to  be  found  in  the  last — ninth — segment  and  certainly 
independent  of  the  alimentary  canal  and  of  the  genital  organs. 

The  origin  of  this  organ  is  thought  to  be  a sac-like  invagination  of 
the  integument  (Plate  10,  Fig.  113).  The  most  external  part  forming 
the  terminal  tube,  the  more  internal  one  a cystiform  enlargement, 
from  the  bottom  of  which  the  two  pedunculate  bodies  originate,  the 
latter  consequently  being  nothing  but  modified  hairs  derived  from 
the  hypoderm  surrounding  the  capsule. 

In  this  way  it  is  evident  that  in  the  young  larva  which  has  not 
yet  undergone  any  molt  there  will  be  a primitive  organ  with  only  one 
pair  of  pedunculate  bodies.  At  each  successive  molt  the  chitinous 
stratum  of  the  organ  remains  in  place,  involved  by  a new  stratum 
formed  around  it  by  secretion  from  the  hypoderm,  and  the  old  cap- 
sule is  pushed  back  distally.  The  new  layer  consequently  forms  a 
new  cyst  with  a transverse  division  separating  two  halves  in  the 
anterior  of  which  two  new  pedunculate  bodies  are  formed,  this  being 
the  new  organ,  while  the  posterior  half  consists  of  all  that  existed 
before.  In  this  manner,  with  the  successive  molts,  an  increase  in  the 
number  of  the  cysts  and  of  the  pedunculate  bodies  is  brought  about; 
the  capsule  wall  which  is  thinner  when  it  belongs  to  a younger  stage; 


40 


THE  EARLY  STAGES  OF  TABANIDiE 


is  no  more  easily  visible  in  the  final  form.  This  hypothesis  is,  accord- 
ing to  Paoli,  the  only  one  which  explains  satisfactorily  the  manner 
in  which  this  strange  organ  is  formed,  and  it  is  sufficiently  supported 
by  observation.  In  fact,  the  whole  organ  is  covered  by  the  hypo- 
derm,  the  latter  not  being  very  different  from  that  which  covers  the 
body  integument  internally. 

In  a preparation  of  a whole  larva  which  had  molted  recently 
Graber’ s organ  was  made  up  of  five  pairs  of  black  pedunculate  bodies, 
and  one  pair,  anteriorly  located,  had  the  pedunculate  bodies  already 
formed  but  entirely  colorless;  this  capsule  was’  evidently  recently 
formed  and  its  pedunculate  bodies  were  not  yet  completely  chitinized 
and  fully  colored. 

The  further  fact,  that  the  number  of  pairs  of  pedunculate  bodies 
increases  with  the  age  of  the  larva,  clearly  demonstrates  that  they 
are  formed  successively,  and  inasmuch  as  we  have  to  deal  with  an 
organ  dependent  on  the  integument,  these  successive  formations  must 
have  something  to  do  with  the  molts  as  modifications  of  the  integu- 
ment. All  the  cells  and  nuclei  described  by  Graber  as  surrounding 
the  cyst  and  the  tube  consequently  are  merely  cells  and  nuclei  of  the 
hypoderm  which  surrounds  the  whole  organ. 

Paoli  discusses  further  the  muscles  and  ligaments  observed  by 
Graber.  It  is  found  that  the  muscles  as  well  as  the  nerves  are  at- 
tached to  the  anterior  capsule,  which  alone  forms  the  living  and 
functioning  part  of  the  organ,  while  the  remaining  part  is  to  be  con- 
sidered dead,  having  functioned  in  previous  stages  of  development. 

While  Graber  described  only  one  pair  of  muscles,  Paoli  observed 
four  pairs  and  stated  that  probably  Graber’ s second  pair  of  nerves 
corresponds  to  the  second  pair  of  muscles.  Two  large  anterior 
muscles  are  attached  to  the  anterior  part  of  the  capsule  with  a large 
surface  of  insertion  extending  from  the  dorsal  posterior  side  of  the 
capsule  upwards  almost  to  contact  with  one  another.  These  muscles 
are  those  seen  by  Graber  who  assumed  that  they  were  attached 
with  the  other  end  in  the  fifth  abdominal  segment,  the  seventh  as 
he  erroneously  assumed.  According  to  Paoli,  they  are  shorter  and 
inserted  in  the  sulcus  between  the  sixth  and  seventh  abdominal 
segments ; they  diverge  anteriorly  passing  across  the  two  large  tracheal 
trunks.  By  the  contraction  of  these  muscles  the  organ  is  displaced 
towards  the  head. 


WERNER  MARCHAND 


41 


The  second  pair  of  muscles  corresponds  probably  to  the  elements 
which  Graber  assumed  to  be  a second  pair  of  nerves;  their  diameter 
is  about  the  same  as  in  those  of  the  first  pair;  they  are  attached  at 
the  sides  of  the  posterior  parts  of  the  cyst,  extending  backwards 
almost  parallel  to  one  another,  and  finally  are  found  to  be  inserted 
at  the  sides  of  the  opening  of  the  terminal  tube,  in  the  furrow  be- 
tween the  eighth  and  ninth  abdominal  segments.  The  action  of  these 
muscles  consequently  is  directly  opposed  to  that  of  the  first  pair, 
and  displaces  the  organ  posteriorly. 

The  two  pairs  of  muscles  described  are  the  most  important  and  are 
attached  at  the  lateral  walls  of  the  cyst;  the  two  following  pairs  are 
attached  to  the  posterior  border  of  the  ventral  side  of  the  cyst.  Of 
these,  the  third  pair,  more  exteriorly  located,  is  formed  by  two  di- 
vergent muscles  which  are  inserted  at  the  sides  of  the  ventral  body 
wall,  somewhat  behind  the  sulcate  prominence  bearing  the  anus. 
The  two  muscles  of  the  fourth  pair  are  also  attached  to  the  ventral 
body  wall,  near  the  median  line,  in  front  of  the  lip-like  hook-bearing 
expansion.  Hence  it  appears  that  these  two  pairs  of  muscles  pull 
the  organ  in  the  ventral  direction,  between  the  two  large  principal 
tracheae. 

Membranous  ligaments  are  also  described  by  Paoli.  In  addition  to 
the  four  pairs  of  muscles  and  the  terminal  tube,  the  organ  is  held  in 
position  by  membranes,  the  largest  of  which  has  the  shape  of  a coni- 
cal cap  involving  the  capsule  anteriorly  and  attached  to  the  poste- 
rior extremity  of  the  dorsal  blood  vessel,  which  terminates  not  far 
from  the  limit  between  the  seventh  and  eighth  abdominal  segment. 
Other  membranes,  one  on  each  side,  envelop  the  basis  of  the  muscles 
of  the  second  pair,  but  Paoli  was  not  able  to  find  the  insertion  of 
their  free  end. 

Concerning  the  nerves  belonging  to  the  organ,  Graber  claimed 
that  it  was  richly  innervated,  describing  two  large  nerves  which 
formed  ganglion-like  masses  near  the  capsule.  These  nerves,  how- 
ever, are  muscles,  according  to  Paoli,  which  are  slightly  inflated  at 
their  base.  It  is  to  be  noted,  however,  that  the  ganglion-like  swell- 
ings were  reported  by  Graber  not  for  the  large  nerves,  but  for  the 
first  thin  pair.  Paoli  found  two  nerves  which  anastomose  and  fuse 
to  a short  tract,  further  on  redividing  into  two  branches,  one  more 


42 


THE  EARLY  STAGES  OF  TABANID^E 


slender  which  goes  to  the  base  of  the  muscles  of  the  second  pair, 
one  larger  which,  extending  below  the  muscles  themselves  to  the  an- 
terior part  of  the  capsule,  corresponding  to  the  pedunculi,  while  it  is 
not  possible  to  affirm  with  certainty  that  it  has  a relation  with  these. 
Paoli  seems  not  to  attach  any  importance  to  the  behavior  of  this 
nerve. 

All  the  muscles,  in  addition,  receive  in  their  course  the  termina- 
tions of  other  nerves.  Those  of  the  first  pair,  not  far  from  their 
place  of  insertion  in  the  cyst,  receive  two  branches  derived  from  a 
nerve  which  bifurcates  in  the  neighborhood  of  the  muscle  itself,  in 
fact  so  near  that  it  gives  the  appearance  that  the  nerves  go  to  the 
cyst. 

All  the  nerves  and  muscles  described  are  related  to  the  head  cap- 
sule which  encloses  the  first  pair  of  pedunculate  bodies.  The  re- 
maining section,  which  contains  the  dead  parts  of  the  organ,  receives 
towards  its  middle  the  endings  of  a slender  nerve  which,  while  it  is  a 
single  one  in  the  region  of  the  hypoderm,  branches  into  a large  num- 
ber of  thin  ramifications. 

Concerning  the  function  of  Graber’s  organ,  Paoli  likewise  dis- 
misses the  hypothesis  of  a glandular  function,  there  being  no  indi- 
cation whatever  of  the  presence  of  glandular  cells. 

That  the  organ  should  have  an  auditory  function  is  also  thought  to 
be  of  little  probability,  especially  as  it  would  differ  from  other  cystoid 
auditory  organs,  by  having  its  inner  surface  covered  with  chitin, 
bearing  no  hairs,  but  instead  of  them,  pedunculate  bodies.  Otoliths 
are,  moreover,  practically  never  found  among  insects,  and  the  organ 
in  question  would  be  unique  also  in  this  respect.  Furthermore,  in 
this  organ,  there  seems  to  be  no  special  preponderance  of  nerves  as  one 
would  suppose  to  be  the  case  in  a sense  organ,  but  rather  a prepond- 
erance of  muscular  apparatus,  in  as  far  as  numerous  long  muscles  are 
connected  with  it  in  various  directions,  these  muscles  being  richly 
innervated.  The  organ  is  consequently,  according  to  Paoli,  destined 
chiefly  to  be  set  in  motion  or  to  be  extended  in  various  directions; 
in  fact,  displacements  were  observed  in  anterior,  posterior,  and  ver- 
tical directions,  and  also  lateral  displacement  seems  to  be  possible 
if  the  muscles  acted  on  one  side  alone. 


WERNER  MARCIIAND 


43 


Paoli,  in  seeking  for  the  function  of  this  organ,  recalls  his  own 
observation  of  the  larvae  producing  a crackling  noise,  under  water 
as  well  as  in  the  air,  similar  to  the  sound  produced  by  small  electric 
discharges.  He  thinks  that  these  sounds  might  be  produced  by 
means  of  this  organ.  By  the  action  of  the  muscles  the  cyst  would 
be  subjected  to  deformations  by  means  of  which  the  pedunculate 
bodies  would  be  caused  to  hit  against  one  another.  The  elastic 
membranes  also  would  aid  in  this  process  as  well  as  the  chitinous  walls 
of  the  capsule.  The  two  large  tracheag  would  serve  as  resonators. 

The  objection  that  such  an  organ  of  sound  should  lie  at  the  surface 
of  the  body  rather  than  in  its  interior,  is  met  with  the  consideration 
that  these  larvae  are  aquatic,  living  below  the  surface  of  the  water 
or  in  the  mud,  where  the  possession  of  an  organ  producing  sound  in 
the  air  would  be  of  little  value.  The  song  of  the  Cicada  becomes 
much  feebler  when  the  insect  is  submerged  under  water,  but  the 
larva  in  question  produces  its  sound  as  well  under  the  water  as  in 
the  air.  As  the  pedunculate  bodies  are  enclosed  in  a liquid,  the  con- 
duction of  the  sound  would  also  occur  easily  in  a liquid  element.  If 
the  peculiar  sound  produced  by  the  larva  was  not  caused  by  the  action 
of  this  organ,  there  would  be,  according  to  Paoli,  no  other  organ  by 
which  it  could  possibly  be  produced.  Paoli  has  consequently  de- 
cided to  assign  to  the  organ  a sound-producing  function.7 

7 1 have  in  the  meantime  found  occasion  to  observe  tabanid  larvas,  and  was 
eager  to  test  Paoli’s  observations.  In  fact  the  crackling  noise  was  freely  produced 
by  full  grown  Tabanus  atratus  larvae,  and  also,  in  harmony  with  Paoli’s  state- 
ment, it  was  chiefly  heard  when  the  larvae  were  disturbed  and  defending  them- 
selves with  their  sharp  mandibles.  The  coincidence  of  the  two  phenomena  was 
so  close  that  I am  bound  to  assume  that  the  sound  is  produced  by  means  of  the 
mandibles.  As  is  well  known,  the  mandibles  of  tabanid  larvae  are  strongly  chit- 
inized  and  provided  with  a serrate  inner  edge.  Very  near  this  and  slightly  be- 
low, the  maxillae,  also  chitinous,  are  situated.  In  the  act  of  biting,  the  mandibles 
are  suddenly  exserted  with  considerable  force  and  it  is  conceivable  that  in  this 
act  their  serrate  edge  strikes  the  maxillae,  producing  a sharp  sound.  The  action 
itself  may  have  some  physiological  importance,  in  as  far  as  it  serves  in  the  lacera- 
tion of  the  skin  or  body  wall  of  animals  attacked,  while  the  sound  produced  ap- 
pears to  me  more  accidental,  as,  for  instance,  the  gnashing  of  teeth  in  carnivora. 

Hence  it  is  not  likely  that  Graber’s  organ  has  the  function  ascribed  to  it  by 
Paoli.  Also  Paoli’s  opposition  to  Graber’s  view  is  not  well  founded  in  as  far  as 
he  himself  assumes  that  the  pedunculate  bodies  are  modified  hairs.  They  could 


CHRYSOPS  (MEIGEN),  EARLY  STAGES  IN  GENERAL. 

In  Fabricius’  Sy sterna  Entomologies  and  Entomologia  Systematica 
I have  found  no  statement  of  the  early  stages  of  any  species  of  this 
genus. 

Zetterstedt  says  that,  according  to  Fabricius,  the  larvae  live  in  the 
ground.  However,  Zetterstedt  himself  saw  a large  number  of  appar- 
ently new  emerged  adults  at  the  borders  of  a lake,  which  would 
indicate  an  aquatic  habitat. 

According  to  Hart,  the  larvae  and  pupae  of  Chrysops,  as  well  as  the 
imago,  are  distinguishable  from  those  of  Tabanus  by  the  antennal 
structure.  Otherwise  the  Chrysops  larvae  closely  resemble  in 
structure  small  or  young  Tabanus  larvae.  The  dull  pubescent  annuli 
are  partly  present  in  Chrysops , but  the  longitudinal  lateral  lines,  ex- 
cept on  the  prothorax,  are  shining  and  almost  entirely  without  pu- 
bescence. There  is  very  little  pubescence  here,  however,  in  some 
young  Tabanus  larvae.  The  species  described  by  Hart  ( Chrysops 
vittatus  Wied.)  is  easily  recognized  by  the  dark  patch  on  the  last 
segment. 

The  distinguishing  characteristics  given  for  larvae  of  Chrysops 
compared  with  those  of  Tabanus  are  the  following:  “Last  antennal 
joint  much  longer  than  the  one  preceding,  dorsal  areas  of  thorax 
striated  like  those  of  abdomen/’  Neave  compared  the  syphon  of  the 

consequently  take  the  place  of  the  auditory  hairs  which  are  missing,  and  as  the 
pedunculate  bodies,  which  in  reality  are  modified  hairs,  would  assume  the  func- 
tion of  otoliths,  there  would  be  no  exception  to  the  general  rule  that  true  oto- 
liths are  not  found  among  insects.  Functionally  the  organ  could  well  belong  to 
the  group  where  it  was  placed  by  Graber.  Also  the  fact  remains  that,  even 
according  to  Paoli,  nerves  go  to  the  fundus  of  the  cyst,  where  the  pedunculate 
bodies  are  attached.  The  problem  cannot  be  regarded  as  solved  by  Paoli’s 
hypothesis.  On  the  other  hand,  to  assume  a true  auditory  function  seems  equally 
hazardous;  it  seems  more  probable  that  the  organ  might  play  a part  in  the  senses 
of  equilibrium  and  orientation,  which,  however,  can  only  be  determined  by 
further  investigation. 


44 


WERNER  MARCHAND 


45 


Ghrysops  larva  with  that  of  Hcematopota  (Plate  5,  Figs.  73  and  74), 
and  found  the  syphon  much  more  elongated  in  Chrysops. 

Beling  (1882)  is  the  first  to  describe  the  pupa  of  a Chrysops , which 
had  been  found  at  the  edge  of  a brook.  A Chrysops  larva  which 
pupated  became  known  first  through  Hart  (1895).  This  larva  re- 
mains, until  recently,  the  only  one  described.  After  Hart,  our 
knowledge  is  increased  chiefly  by  Hine,  especially  with  reference  to 
oviposition  and  egg  stage,  on  which  Patton  and  Cragg  have  also 
made  observations.  The  larvae  and  pupae  of  several  African  species 
became  known  through  Neave’s  work  (1915). 

The  little  Chrysops  pupae  have  longer  antennae,  and  the  thoracic 
spiracular  prominence  is  more  nearly  in  a vertical  plane  than  in 
Tabanus,  its  inner  edge  being  more  strongly  elevated.  The  lower 
free  edge  is  crossed  by  sharp  folds,  making  it  serrated.  In  Chrysops 
the  abdominal  spiracles  are  subcylindric  near  the  apex;  the  spinose 
fringes  consist  of  long  teeth  only;  and  the  terminal  teeth  are  long 
and  rather  narrow  at  the  base. 

The  distinguishing  characteristics  of  the  pupae  are  the  following: 

“Antennae  surpassing  adjacent  margin  of  head;  fringes  of  abdomen  of  long 
spines  only;  inner  margin  of  thoracic  spiracular  prominences  sharply  elevated, 
lower  margin  serrate-edged;  abdominal  spiracles  slender,  subcylindrical  near 
apex;  size  small.” 

The  eggs  of  Chrysops  are  deposited,  as  we  learn  from  Hart,  “in  one 
flat  tier,  forming  an  oval  or  diamond-shaped  area,  pointed  at  one  or 
both  ends.”  We  know,  however,  from  Hine’s  observation  on  Chry- 
sops celer , that  there  are  exceptions  to  this  rule  and  there  are 
species  of  Chrysops  which  oviposit  in  several  layers  after  the  fashion 
of  Tabanus.  Most  of  the  eggs  of  Chrysops  are  black,  according  to 
Hine,  and  are  placed  in  a single  layer,  but  there  are  exceptions  to 
this,  for  the  eggs  of  Chrysops  celer  are  never  darker  in  color  than 
brown,  and  are  placed  in  at  least  three  layers  one  upon  the  other. 

With  regard  to  the  habits  of  the  pupal  stage,  Hine’s  observations 
are  of  interest,  as  he  saw  around  fresh  water  ponds  myriads  of  pupa 
skins  of  Chrysops  with  just  the  anterior  end  projecting  above  the 
surface  of  the  ground. 

The  following  are  the  notes  which  we  possess  on  various  species 
of  Chrysops,  arranged  alphabetically. 


46 


THE  EARLY  STAGES  OF  TABANIDiE 


Chrysops  bimaculosa  Neave. — An  African  species,  allied  to  Chry- 
sops  centurionis  Aust.,  discovered  by  Neave  (1915)  on  Mt.  Mlanje, 
in  southern  Nyasaland.  A typical  male  and  female  and  one  other  of 
each  sex  were  bred  in  October  and  November,  1913;  one  female  was 
collected  in  November,  1912. 

Of  the  four  individuals  above  mentioned  three  were  bred  from  col- 
lected pupse  and  the  fourth  from  a larva  which  resembled  that  of 
Chrysops  longicornis,  though  considerably  larger,  with  a somewhat 
less  strongly  pigmented  anal  segment  and  with  well  marked  hairs  on 
the  syphon. 

The  hooks  of  the  pupal  aster,  especially  the  upper  and  middle 
pairs,  are  decidedly  elongate  (Plate  13,  Fig.  167,  a,  b,  c). 

Imago,  larvae,  and  pupae  had  been  taken  on  the  banks  of  a wooded 
stream. 

Chrysops  callidus  Osten  Sacken. — A common  and  widely  distrib- 
uted species,  recorded  from  most  of  the  eastern  states,  reaching 
Florida  in  the  South,  Indiana  in  the  West,  but  apparently  not  occur- 
ring in  northern  New  England.  Hine  has  described  the  oviposition 
of  this  species,  indeed  has  watched  the  entire  process  of  oviposition, 
which  usually  occupies  from  20  minutes  to  half  an  hour,  during 
which  time  something  like  one  to  three  hundred  eggs  are  laid. 

The  female  alights  on  the  leaf  head  downwards  and  begins  to  push 
the  tip  of  the  abdomen  forward  towards  the  sternum  of  the  thorax, 
placing  the  protruding  end  of  an  egg  against  the  leaf.  This  end  sticks 
fast  and  she  then  moves  the  tip  of  the  abdomen  backwards  until 
normal  position  is  reached  and  the  egg  is  free.  By  the  same  move- 
ment one  or  two  eggs  are  then  placed  to  one  side  of  this  one  and  two 
or  three  on  the  other  side  of  it.  The  unfinished  end  is  soon  observed 
to  be  V-shaped,  the  female  moving  gradually  forward  and  placing  the 
end  of  the  abdomen  to  one  side  of  the  V and  depositing  eggs  along 
down  until  the  apex  is  reached,  then  changing  the  tip  of  the  abdomen 
to  the  outer  part  of  the  other  side  of  the  V and  placing  eggs  along  it 
down  to  the  apex  on  this  side. 

This  process  is  kept  up,  the  female  changing  regularly  to  the  outer 
part  of  the  opposite  side  of  the  V each  time  the  apex  is  reached. 
Between  9 o’clock  and  noon  seems  to  be  the  favorite  time  of  day  for 


WERNER  MARCHAND 


47 


oviposition,  as  with  other  species  of  Chrysops  and  Tabanus;  Hine  has 
seldom  observed  females  ovipositing  at  other  hours  of  the  day. 

The  eggs  when  first  laid  are  clear  white  but  gradually  get  darker 
until  they  become  permanently  dark  brown  or  black.  It  took  eggs 
of  Chrysops  callidus  5 or  6 days  to  hatch,  and  it  required  about  a day 
longer  in  the  case  where  eggs  were  kept  in  the  shade  the  whole  time 
than  in  cases  where  the  eggs  were  in  the  sun  during  the  day.8 

The  writer  has  made  some  additional  observations  on  Chrysops 
callidus , which  are  published  elsewhere. 

Chrysops  celer  Osten  Sacken. — A species  recorded  from  Maine, 
Massachusetts,  Pennsylvania,  New  Jersey,  Ohio,  and  North  Caro- 
lina. This  species  is  common  in  Ohio  during  the  latter  half  of  May. 
The  eggs  have  been  observed  commonly  by  Hine  along  the  margin 
of  ponds  and  artificial  lakes,  clinging  to  various  kinds  of  foliage  over- 
hanging the  water.  The  female  has  been  observed  ovipositing  on 
different  occasions,  and  is  the  only  species  of  the  genus  placing  its 
eggs  in  masses  composed  of  layers  one  above  the  other  as  in  Tabanus. 

Chrysops  dispar  Fabricius. — This  species  is  widely  distributed  in 
India,  Ceylon,  Malay,  and  adjacent  parts.  We  possess  some  infor- 
mation on  its  early  stages  through  the  work  of  Patton  and  Cragg  in 
Madras  (1913). 

8 In  the  summer  of  1916,  I collected  the  eggs  of  Chrysops  callidus  O.  S.,  in 
Princeton,  N.  J.,  from  which  the  young  larvae  were  obtained.  These  are  half 
transparent,  whitish,  and  their  structure  is  analogous  to  that  of  most  tabanid 
larvae,  differing,  however,  from  the  young  larvae  of  Tabanus,  as  far  as  known  to 
me,  by  having  the  main  tracheal  trunks  not  inflated,  but  of  about  equal  diame- 
ter all  along  their  course.  This  character  (“not  provided  with  air  sacs”)  is, 
however,  given  by  Patton  and  Cragg  for  all  “small  tabanids”  observed  in  Mad- 
ras, including  species  of  Chrysops,  Tabanus,  and  Hczmatopota.  It  causes  the  larva 
of  Chrysops  callidus  to  sink  to  the  bottom  instead  of  floating  to  the  surface.  The 
larvae  of  this  species  molt  soon  after  hatching,  and  can  live  under  water  for  a 
considerable  time,  but  as  all  the  larvae  died  in  young  stages,  I am  unable  to 
say  what  their  further  habits  are,  and  whether  they  spend  most  of  their  life  in 
the  water  or  later  on  invade  the  mud  of  the  shore.  At  a pond  where  large 
numbers  of  Chrysops  had  oviposited  the  previous  summer,  in  spring  no  larvae 
could  be  detected  in  the  mud  of  the  margin,  while  other  tabanid  larvae  were 
numerous. 

For  further  details  see  Marchand,  J.  N.  Y.  Entomol.  Soc.,  1917,  xxv,  149. 


48 


THE  EARLY  STAGES  OE  TABANIDiE 


Chrysops  dispar  lays  its  eggs,  as  do  all  the  small  species  of  tabanids 
observed  by  these  authors,  invariably  on  blades  of  grass  just  at  the 
edge  of  a shallow  stream,  or  on  the  leaves  of  the  lotus  plant  at  the 
edges  of  small  ponds,  but  never  over  deep  water. 

In  Madras  the  smaller  species  of  tabanids  always  lay  their  eggs  in 
the  afternoon,  commencing  about  4 p.m.  Chrysops  dispar  has  been 
seen  ovipositing  as  late  as  7 p.m.  An  egg  mass  of  this  species,  on  a 
blade  of  grass,  and  also  a single  egg,  is  figured  by  these  authors  (Plate 
1,  Figs.  14  and  15),  but  no  description  of  the  larva  is  given. 

The  larvae  of  the  smaller  species  of  tabanids  (including  Chrysops 
dispar)  contain  no  air  sacs,  according  to  these  authors,  and  if  they 
fall  into  deep  water  they  die.  It  is  important  to  recognize  this  in 
breeding  experiments  and  to  place  them  in  trays  with  only  a little 
water. 

Patton  and  Cragg’s  text-book  contains  notes  on  smaller  species  of 
tabanids  some  of  which  may  apply  to  this  species,  but  are  not  clearly 
referred  to  it. 

Chrysops  indus  Osten  Sacken. — This  species  is  recorded  from  New 
Jersey,  New  York,  Canada,  and  Ohio.  According  to  Hine,  it  appears 
in  Ohio  usually  by  the  middle  of  May.  It  is  the  first  species  to 
appear  in  the  spring  and  females  have  been  observed  ovipositing  on 
plants  growing  along  the  margin  of  a small  lake  on  the  University 
grounds  in  Columbus,  Ohio.  The  eggs  are  placed  in  single  layers  on 
grass  blades  that  hang  over  the  edge  of  the  water. 

Chrysops  longicornis  Macquart. — This  is  an  African  species,  the 
early  stages  of  which  have  become  known  through  the  work  of  Neave 
(1915).  The  species  is  the  most  abundant  of  the  genus  in  the  neigh- 
borhood of  Mt.  Mlanje,  southern  Nyasaland,  where  Neave’s  investi- 
gations were  carried  on.  The  flies  prefer  well  wooded  localities  and 
Neave  thinks  it  probable  that  all  stages  exist  throughout  the  year. 

The  larvae  were  first  discovered  at  the  end  of  August,  1913,  and  to 
Neave’ s surprise,  in  view  of  the  habits  of  the  adults,  were  found  in 
the  mud  of  a small  marsh  and  stream  bed  in  an  open  spot  with  only 
comparatively  thin  woodland  near  it.  Many  other  examples  were 
subsequently  taken,  both  in  similar  places  and  in  less  unexpected 
spots  on  the  banks  of  wooded  streams,  etc.  Except  for  an  occasional 


WERNER  MARCHAND 


49 


freshly  emerged  individual,  the  adult  flies  were  not  taken  in  these 
open  places  and  appear  therefore  to  migrate  from  them  after  emer- 
gence and  to  return  to  them  for  the  purpose  of  oviposition.  If  this 
is  the  case,  it  is  another  example  of  the  possibilities  of  error  in  search- 
ing for  the  breeding  place  of  a species  in  the  spot  most  frequented  by 
the  adults. 

The  larvae,  figured  by  Neave  but  not  described,  were  obtained  in 
considerable  numbers  from  September  on,  a few  being  still  obtain- 
able even  in  January  and  February.  In  the  figure  (Plate  5,  Fig.  72) 
the  eleventh  segment  shows  a broad  dark  pigmented  band,  dorsally 
reaching  somewhat  anteriorly  to  the  middle  of  the  segment,  ventrally 
including  the  anal  prominence,  while  the  tube-shaped  posterior  third 
of  the  segment  appears  to  be  free  from  pigment,  as  also  the  slender 
tube-like  twelfth  segment  (syphon).  The  circular  ridges  show  only 
traces  of  pigmentation.  A good  illustration  of  the  pupa  is  given 
(Plate  11,  Fig.  130),  which,  however,  shows  no  peculiar  characteristics 
by  which  it  could  be  differentiated  from  a Tabanus  pupa.  The  pupal 
asters  of  male  and  female  pupae  are  shown  and  differ  considerably 
(Plate  13,  Fig.  171,  a , b). 

Chrysops  magnified,  var.  inornata,  Austen. — An  African  species, 
according  to  Neave,  not  rare  in  the  Mlanje  district  of  southern 
Nyasaland,  during  the  rains  from  October  to  April. 

This  species  was  bred  from  the  larva  by  Neave,  but  the  larva  so 
closely  resembles  that  of  Chrysops  longicornis  Macq.  that  Neave 
never  succeeded  in  separating  it  satisfactorily,  since  in  both  species 
the  usually  distinctive  characters  of  the  pigmented  anal  segment  and 
syphon  were  variable. 

The  pupal  aster  (Plate  13,  Fig.  166,  a,  b)  resembles  that  of  Chry- 
sops longicornis , but  the  middle  pair  of  hooks  is  stouter  and  somewhat 
more  curved,  and  the  shape  differs  somewhat,  especially  in  the  male. 
The  pupal  asters  of  the  male  and  female  are  illustrated. 

Chrysops  mcechus  Osten  Sacken. — A species  recorded  from  New 
Jersey,  District  of  Columbia,  Illinois,  Ohio,  and  Kentucky.  Hine 
has  observed  the  females  ovipositing  on  foliage  overhanging  a mill 
race  at  Georgesville,  Ohio,  June  4,  1899,  but  does  not  describe  the 
eggs. 


50 


THE  EARLY  STAGES  OE  TABANID^E 


Chrysops  mcerens  Walker  (synonym  cestuans  van  der  Wulp). — 
Recorded  from  Illinois,  North  Dakota,  Wisconsin,  and  Ohio.  This  is 
the  species  in  which  oviposition  was  first  observed  by  Hart  (1895), 
who  saw  these  flies  from  August  3 to  10  flying  among  the  marginal 
rushes  of  Fourth  Lake,  Sand  Lake,  and  Slough  Lake  in  Lake  County, 
Illinois,  and  ovipositing  on  the  stems  of  the  rushes. 

The  egg  is  described  by  Hart  as  follows: 

“Egg. — [Plate  1,  Fig.  2,  egg  masses.]  Length  1.6  mm.,  diameter  0.25  mm., 
cylindrical  with  rounded  ends,  straight  or  slightly  curved,  smooth,  slightly  opaque, 
cream  color  when  laid,  becoming  dark  fuscous  brown,  placed  in  a single  flat 
layer,  obliquely  stacked  as  in  Tabanus,  about  one  fourth  of  the  length  of  each 
egg  being  visible  at  the  surface,  the  remaining  three  fourths  being  covered  by 
those  stacked  against  it.  The  mass  is  about  10  mm.  long  and  3 or  4 mm.  wide, 
its  outline  variable,  usually  diamond-shaped,  both  ends  pointed,  or  at  one  end 
short  or  truncate,  making  it  more  or  less  triangular.” 

Eggs  of  this  species  were  observed  by  Hine  (1906)  at  Sandusky, 
Ohio,  during  the  first  days  of  July  and  were  present  in  varying  num- 
bers during  the  following  two  months. 

While  the  female  is  ovipositing  she  is  not  easily  disturbed;  conse- 
quently one  has  an  excellent  opportunity  to  watch  the  procedure. 
An  illustration  given  by  Hine  (Plate  1,  Fig.  1)  was  made  from  a 
photograph  of  a living  specimen  which  was  found  in  the  act  of  egg 
laying  and  was  carried,  with  the  leaf,  to  the  laboratory  where  the 
picture  was  taken.  “During  the  whole  time,”  says  Fline,  “she  con- 
tinued ovipositing  without  showing  any  signs  that  she  was  aware  of 
what  was  going  on  or  that  she  had  any  concern  for  the  welfare  of 
her  eggs.” 

The  method  of  placing  the  eggs  is  similar  to  that  recorded  for 
Chrysops  callidus. 

The  female  alights  on  the  leaf  with  her  head  downwards  and  begins  the  process 
by  pushing  the  tip  of  the  abdomen  forward  towards  the  under  part  of  the  thorax 
and  placing  the  protruding  end  of  an  egg  against  the  leaf.  The  end  sticks  fast 
in  consequence  of  the  glue-like  substance  which  accompanies  it,  and  she  then 
moves  the  tip  of  the  abdomen  back  to  its  normal  position,  thus  freeing  the  egg. 
By  similar  movements  one  or  two  eggs  are  placed  on  one  side  of  the  first,  and  two 
or  three  on  the  other  side  of  it.  The  unfinished  end  soon  becomes  V-shaped; 
she  moves  slowly  forward  and  lifts  the  tip  of  the  abdomen  to  one  side  of  the  V 


WERNER  MARCHAND 


51 


and  places  eggs  along  it  downwards  until  the  apex  is  reached;  then  changes  to 
the  other  side  of  the  V and  places  eggs  along  it,  downwards  to  the  apex  on  this 
side.  It  was  noted  in  specimens  of  this  species  that  sometimes  a female  would 
place  as  many  as  three  rows  of  eggs  on  one  side,  one  after  the  other,  before  chang- 
ing to  the  opposite  side.  It  is  only  necessary  to  study  a mass  of  these  eggs  in 
order  to  see  the  precision  with  which  the  different  specimens  are  arranged. 

The  eggs  are  placed  on  various  aquatic  plants,  often  standing  in 
rather  deep  water  and  at  times  as  much  as  20  rods  from  shore.  Hine 
always  found  them  on  scattering  plants  around  the  edges  of  grassy 
areas  and  not  back  among  the  dense  growth;  consequently  they  are 
easily  seen,  not  only  on  account  of  their  conspicuous  location,  but  also 
because  of  their  shining  black  color,  which  contrasts  strongly  with 
the  green  leaves  to  which  they  are  attached. 

Their  coloration  renders  the  egg  clusters  conspicuous,  and  Hine 
suggests  that  hand  picking  might  be  of  consequence  in  the  control  of 
Chrysops.  In  order  to  demonstrate  what  could  be  done  in  the  way  of 
gathering  eggs  of  this  species,  Hine  went  out  on  the  morning  of  July 
17,  in  Ohio,  in  a small  rowboat,  and  collected  for  an  hour.  At  the 
end  of  this  time  a count  showed  433  masses,  and  an  average  of  250 
specimens  to  each  mass,  a result  obtained  by  counting  several  and 
striking  the  average,  giving  a total  of  108,250  single  eggs  taken  as  a 
result  of  the  hour’s  work. 

Eggs  of  Chrysops  mosrens , laid  from  8.45  to  9.30  a.m.  on  July  13, 
hatched  before  noon  of  July  19,  thus  making  the  incubation  period 
6 days.  This  is  the  shortest  incubation  period  Hine  has  observed 
for  any  species  of  Tabanidae. 

Of  the  larvae,  Hine  says  that  after  hatching  they  drop  into  the 
water,  and  he  states  that,  in  the  natural  breeding  grounds  of  the 
flies,  it  is  almost  impossible  to  find  the  very  small  larvae  after  they 
have  dropped  from  the  eggs  and  have  become  more  or  less  scattered 
among  the  debris  which  is  usually  plentiful  in  these  places. 

In  order  to  ascertain  whether  the  young  larvae  can  be  killed  by 
spreading  a film  of  kerosene  on  the  surface  of  stagnant  water  over 
which  eggs  are  placed,  Hine  (1906)  performed  some  experiments.  A 
tank  of  water  was  used,  on  the  surface  of  which  half  a pint  of  kerosene 
was  placed  to  each  square  yard  of  surface.  Sparganiunt  leaves  to 
which  the  eggs  were  attached  were  brought  in  from  the  marsh  and 


IL  GF  ILL  UQ. 


52 


THE  EARLY  STAGES  OE  TAB  ANTE)  iE 


put  into  a bottle  as  one  would  arrange  a bouquet,  and  this  was  placed 
on  the  bottom  of  the  tank  so  that  the  parts  of  the  leaves  to  which  the 
eggs  were  attached  were  a foot  or  more  above  the  surface  of  the 
water  which  contained  the  layer  of  kerosene.  Even  under  these 
conditions  an  exact  count  could  not  be  obtained,  because  the  kero- 
sene appeared  to  affect  different  specimens  differently.  Some  were 
killed  very  quickly,  some  died  after  an  hour  or  more,  while  others  did 
not  appear  to  suffer  particular  inconvenience  from  the  treatment. 
Further  observation  is  necessary  to  be  able  to  give  conclusive  state- 
ments regarding  the  matter. 

Chrysops  relictus  Meigen. — A European  species,  and  the  first 
species  of  the  genus  in  which  reliable  data  were  obtained,  by  Beling 
(1876),  on  the  pupal  stage.  From  three  pupae  found  on  July  16, 
1876,  in  the  sand  of  the  border  of  a small  meadow  brook,  two  imagos 
were  produced  on  July  24  and  25.  The  third  did  not  develop. 

Beling’s  description  of  the  pupa  is  as  follows: 

Pupa. — 12  mm.  in  length,  3 mm.  in  diameter,  of  dirty  brownish  yellow  color. 
Head  shining,  strongly  brownish  anteriorly;  lower  frontal  margin  with  four 
broad,  rounded  teeth  in  a transverse  row ; above  these  teeth  two  small  tubercles, 
each  with  two  stiff  brown  moderately  long  hairs;  further  down  posteriorly  two 
similar  tubercles  separated  by  a larger  distance  and  each  bearing  only  one 
such  hair.  Dorsally,  at  the  border  between  the  head  and  thorax,  are  two  brown- 
ish ear-shaped  longitudinal  ridges  diverging  posteriorly.  Antennal  sheaths 
laterally  appressed  to  the  head,  short,  terminating  in  a point,  not  much  marked. 
Abdomen  nine-segmented,  brown,  with  blackish  segmental  incisions,  less  shining 
than  the  head  and  the  leg  and  wing  cases.  First  abdominal  segment  very  short, 
deeply  emarginated  in  the  middle  of  the  anterior  margin;  third  to  eighth  abdominal 
segments  inclusive  dorsally  near  the  posterior  margin  with  a transverse  row  of 
densely  placed  backwardly  appressed,  pale  bristle-like  teeth  of  unequal  length, 
gradually  becoming  longer  on  the  posterior  segments  and  extending  also  over  the 
ventral  surface  of  the  segments.  Anal  segment  ending  in  six  claw-like  spines 
arranged  divergently,  of  which  the  two  upper  ones  are  slightly  smaller  than  the 
remaining  four. 

Chrysops  vittatus  Wiedemann. — A common  species  distributed  all 
over  the  eastern  United  States  as  far  west  as  Kansas  and  Iowa. 
This  is  the  first  species  of  Chrysops  of  which  the  larva  has  been  de- 
scribed (Hart,  1895). 9 The  larvae  were  found,  according  to  Hart,  in 

9 Recently,  in  the  spring  of  1917, 1 have  found  larvae  of  this  species  from  which 
a male  imago  was  reared. 


WERNER  MARCHAND 


53 


connection  with  those  of  Bittacomorpha,  Limnophila,  and  Sialis,  in 
the  weedy,  swampy  little  stream  at  Station  I of  his  entomological 
survey  of  the  Illinois  river  valley.  They  were  quite  common  here, 
occurring  in  the  mud  and  the  mats  of  dead  stems,  rarely  floating  at 
the  surface.  The  first  were  seen  March  28,  but  they  continued  to 
occur  up  to  April  15,  increasing  slightly  in  size.  In  the  breeding  cage 
they  burrowed  in  the  mud  and  through  the  vegetation. 

In  the  latter  part  of  May  the  water  was  allowed  to  dry  up  and  on 
the  28th  all  that  remained  was  poured  off.  From  June  1 to  3 three 
pupae  were  formed  in  the  damp  mass  of  dead  vegetable  matter  resting 
on  the  mud  in  the  cage.  Two  imagos  emerged  June  9,  both  males, 
the  third  failing  to  transform. 

The  coloration  of  the  larva  readily  distinguishes  it  from  other 
known  tabanid  larvae.  Hart’s  description  of  larva  and  pupa  is  quoted 
below. 

“Larva,. — [Plate  3,  Fig.  39.]10  Length  10-15  mm.,  diameter  1.6  mm.  Head 
light  colored,  mouth  parts  pale,  tips  of  maxillary  palpi  in  line  with  end  of  labrum; 
body  whitish,  a mottled  appearance  within,  at  the  middle  of  the  body.” 

“Dorsal  and  ventral  areas  striate,  striae  entire,  distinct,  and  not  very  fine, 
the  lateral  striation  a little  finer,  that  of  the  prothorax  very  fine,  with  a small 
smooth  spot  adjoining  the  smoother  surface  of  its  ventral  area;  the  latter  shorter 
than  the  dorsal,  not  including  the  anterior  pair  of  setae;  median  sulcus  scarcely 
dull-pubescent.  Meso-  and  metathorax  with  lateral  impressed  lines,  and 
dull-pubescent  pale  annuli,  but  the  lateral  lines  almost  without  pubescence. 
Fleshy  false  feet  of  abdominals  rather  prominent,  dorsal  pair  united  into  one, 
there  being  no  narrowing  near  the  median  line;  annuli  very  pale  except  on  the 
last  two  or  three  segments;  last  segment  white  basally,  the  remainder  covered 
with  dull  blackish  microscopic  pubescence  reaching  forwards  to  the  anal  promi- 
nence, a triangular  extension  each  side  of  the  middle  above,  often  a small  spot 
accompanying  each;  respiratory  tube  whitish,  spine  sometimes  projecting.” 

“Tracheal  trunks  sinuate  posteriorly,  crossing  and  recrossing  in  front  of  the 
middle.” 

“Pupa. — [Plate  13,  Figs.  154  and  157.]  Length  9-10  mm.,  diameter  2 mm. 
Light  brownish,  ferruginous,  obsoletely  transversely  wrinkled,  head  and  thorax 
shining,  abdomen  duller.” 


10  In  the  quotations,  as  well  as  in  the  rest  of  the  paper,  the  figure  numbers 
refer  to  the  illustrations  in  the  present  monograph. 


54 


THE  EARLY  STAGES  OF  TABANIDiE 


“Antennal  sheaths  not  very  thick  at  base,  surpassing  the  marginal  angulation 
above  them;  carinated  tubercles  not  prominent,  lateral  notches  broad  and  shallow, 
palpal  sheaths  indefinite,  rather  distant;  setiferous  tubercles  scarcely  darker; 
ocellar  tubercles  replaced  by  pale  dots.  Rima  of  thoracic  spiracles  (Plate  13, 
Fig.  157)  strongly  elevated  from  inner  side,  so  that  the  flat  top  of  the  promi- 
nence is  nearly  vertical,  the  upper  edge  of  the  rimal  border  forming  a sharp  carina 
and  its  anterior  extremity  ending  at  the  tip  of  the  marginal  extension  in  an  acute 
angle;  the  free  lower  edge  is  crossed  by  sharp  ridges,  giving  it  a serrate  profile; 
rima  less  curved  at  middle,  more  strongly  at  each  end,  scarcely  hooked; 
inner  notch  with  radiating  striations.” 

“The  abdominal  fringes  consist  of  a single  row  of  pale  spines  on  each  segment, 
rather  long  except  dorsally  on  the  second,  where  they  are  shorter  and  thicker. 
The  abdominal  spiracular  tubercles  arise  from  a slight  elevation,  tapering  from 
a comparatively  small  base  as  far  as  middle,  thence  nearly  cylindrical  to 
apex,  which  bears  a subcircular  rima;  on  the  anterior  slope  a small  transverse 
groove,  not  longer  than  the  rima;  tubercle  about  as  high  as  its  basal  diameter. 
Last  segment  with  six  nearly  equal  terminal  teeth,  their  points  marking  the 
angles  of  a hexagon;  slender,  even  constricted  at  base,  twice  as  long  as  their 
diameter  near  base.  Lateral  spines  almost  wanting;  ventral  fringe  in  front  of 
anal  tubercle  in  male;  a tuft  of  about  five  spines  on  each  side  in  place  of  this  fringe 
in  the  female.” 

Chrysops  wellmani  Austen. — An  African  species,  which,  according 
to  Neave,  occurs  in  fair  numbers  near  Mt.  Mlanje,  southern  Nyasa- 
land,  from  September  to  January. 

The  larvae  of  this  species  (Plate  3,  Fig.  50),  differ  strikingly  from 
any  of  the  other  Chrysops  larvae  seen  by  Neave,  in  their  strong  pig- 
mentation. In  the  figure  it  is  seen  that  while  segments  1 to  3 are 
free  from  pigmentation,  segments  4 to  11  show  the  regular  tabanid 
pigmentation  on  the  transverse  circular  ridges,  leaving  an  area  around 
the  prolegs  free  from  pigment.  There  are  no  longitudinal  stripes,  but 
on  segment  1 1 there  are  two  subdorsal  dark  spots  (in  addition  to  the 
broad  posterior  band) , traces  of  which  are  also  visible  in  the  figure  of 
the  syphon  of  Chrysops  longicornis. 

The  larvae  were  obtained  in  the  beds  of  forested  streams  with  those 
of  Chrysops  longicornis  and  Chrysops  magnified , var.  inornata , but 
were  much  less  common.  They  were  found  only  between  the  middle 
of  October  and  the  end  of  November.  There  is  considerable  differ- 
ence in  the  hooks  of  the  aster  in  the  two  sexes  of  this  species,  the 
upper  and  lower  hooks,  especially  the  former,  being  much  reduced 


WERNER  MARCHAND 


55 


in  the  female.  The  pupal  asters  of  both  sexes  are  shown  (Plate  13, 
Fig,  168,  a,  b ) « 

Dorcalcemus  fodiens  Austen. — An  African  species,  on  which  some 
observations  have  been  made  by  Neave  (1915)  in  southern  Nyasaland. 

Some  examples  of  what  may  be  the  larvae  of  this  species  were  found, 
though  the  point  could  not  be  decided,  as  Neave  was  obliged  to  leave 
before  they  reached  maturity.  They  were  captured  during  Decem- 
ber, January,  and  February  in  some  swampy  ground  on  which  a patch 
of  maize  was  growing.  These  larvae  were  of  fair  size,  some  30  mm.  in 
length;  the  syphon  was  very  short  and  had  a distinct  pigmented  ring 
on  the  anal  segment  resembling  that  in  Heematopota  larvae.  In  the 
more  mature  specimens  traces  of  intersegmental  pigment  were  present. 

At  the  time  these  larvae  were  captured  no  other  larvae  of  so  large  a 
species  were  obtainable,  and  as  Dorcalcemus  fodiens  is  the  only  large 
tabanid  which  is  on  the  wing  in  March  and  April,  there  are  grounds 
for  thinking  that  the  larvae  belonged  to  that  species. 

Gastroxides  ater  Saunders. — A black  species  of  a genus  allied  to 
Chrysops,  with  elongate  slender  legs  and  long  antennae,  occurring  in 
Pusa,  Bengal,  India  (Maxweli-Leffroy  and  Rowlett,  1909).  The 
larva  is  said  to  breed  in  hollow  trees.  No  more  details  are  available. 
A picture  of  the  adult  is  given  by  Maxweli-Leffroy  and  Rowlett. 

11  In  the  summer  of  1916  I found  eggs  of  another  species  of  Chrysops  which 
differed  considerably  in  appearance  from  the  two  types  described  hitherto. 
These  eggs  were  found  on  the  under  surface  of  leaves  of  the  yellow  pond  lily 
( Nuphar ),  four  or  five  clusters  in  all,  and  one  on  a Pontederia  leaf.  The 
eggs  were  white,  and  placed  vertically  on  the  surface  of  the  leaf,  one  beside  the 
other,  the  cluster  being  roundish  when  seen  from  above,  presenting  an  even 
dull  white  surface  formed  by  the  tips  of  the  eggs,  and  with  clean-cut  vertical 
outer  walls.  After  a few  hours  these  egg  clusters  turned  somewhat  brownish, 
but  never  became  very  dark.  In  one  case  the  female  fly  was  observed  oviposit- 
ing, but  escaped  before  being  captured.  It  appeared  to  belong  to  Chrysops  uni- 
vittatus  or  possibly  Chrysops  lugens.  The  larvae  hatched  within  5 days,  molted 
soon  after  hatching,  and  did  not  differ  appreciably  from  those  of  Chrysops  callidus. 

For  further  details  see  Marchand,  J.  N.  Y.  Entomol.  Soc.,  1917,  xxv,  149. 


GONIOPS  (ALDRICH),  EARLY  STAGES  IN  GENERAL. 


The  following  brief  characteristics  of  the  early  stages  of  Goniops 
are  given  by  Malloch  (1917). 

“ Larva. — Mandibles  stout,  slightly  curved,  apically  truncated;  antennae 
elongate,  3-jointed,  basal  joint  stout,  tapering  apically,  about  twice  as  long  as 
apical  2 combined;  apical  joint  much  shorter  than  preapical;  maxillary  palpi 
2-jointed,  the  apical  joint  slender  and  distinctly  shorter  than  the  basal.  Thoracic 
segments  very  distinctly  tapered  anteriorly,  abdomen  stout,  roughly  oval  in 
outline,  the  whole  body  appearing  pyriform  or  slightly  club-shaped;  abdominal 
segments  with  rather  irregularly  arranged  transverse  series  of  locomotor  tuber- 
cles; spiracular  chamber  in  form  of  a vertical  slit.” 

“Pupa. — Head  without  projecting  thorns;  antennal  sheath  short,  curved 
downward.  Prothorax  about  one-third  as  long  as  mesothorax;  wings  short, 
extending  to  apex  of  first  ventral  abdominal  segment ; apices  of  hind  tarsi  slightly 
surpassing  apices  of  wings.  Armature  of  dorsal  abdominal  segments  consist- 
ing of  stout  thorns  in  a transverse  series,  2 of  which,  near  middle  of  segments 
2 to  7,  are  much  stronger  than  the  others;  later  the  series  are  discontinued  some 
distance  from  margins;  apical  segment  with  three  strong  thorns  on  each  side, 
between  which  are  several  weaker  protuberances.” 

The  eggs  are,  as  stated  by  Malloch,  (after  Walton  (?),  McAtee 
(?)),  usually  deposited  on  the  under  side  of  leaves  of  various  plants, 
and  when  the  larvae  hatch  they  drop  to  the  ground,  living  after- 
wards among  the  decaying  leaves  and  other  vegetable  debris.  They 
are  probably  predacious  like  other  Tabanidae. 

The  egg  masses  are  parasitized  by  a proctotrypid  parasite. 

McAtee  briefly  compares  the  larva  and  pupa  of  Goniops , apparently 
the  only  native  pangoniid  genus  of  which  these  stages  have  been 
described,  with  the  comparatively  well  studied  immature  forms  of 
the  true  tabanids,  such  as  Tabanus  and  Chrysops. 

Hart  says  (quoted  by  McAtee) : 

“All  the  larvae  of  Tabanidae  studied  agree  in  the  following  general  characters: 
Body  tapering  at  both  ends,  which  are  somewhat  pointed;  skin  shining  and  glassy, 
with  opaque  markings  of  a microscopic  felted  pubescence.  The  palpi  have 
short  thick  joints;  the  basal  joint  of  the  antennae  is  quite  short,  and  there  is  a 
bunch  of  stiff  diverging  recurved  hairs  between  each  antenna  and  the  median 
line  above.” 


56 


WERNER  MARCHAND 


57 


The  full  grown  Goniops  larva,  on  the  other  hand,  is  pyriform  and 
not  at  all  pointed  at  the  ends.  Its  skin,  except  on  the  head  and  pro- 
thorax, is  not  shining,  but  everywhere  opaque  and  wrinkled  or  tuber- 
culate.  The  palpi  have  long  slender  joints;  the  basal  joint  of  the 
antenna  is  very  long,  much  exceeding  the  two  terminal  joints,  and  the 
hairs  on  the  antennal  flap  are  flexible  and  attached  to  the  surface 
of  the  head.  The  double  second  joint  of  the  antenna  of  first  stage 
larvae  is  noteworthy. 

Of  the  tabanid  pupa  Hart  says: 

“The  meso thorax  is  one-half  longer  than  the  prothorax  and  the  second  to 
seventh  abdominal  segments  are  encircled  by  continuous  fringes  of  slender  spines.” 

In  Goniops  the  pupal  mesothorax  is  three  times  longer  than  the 
prothorax,  and  the  fringes  of  spines  on  the  abdominal  segments  are 
not  continuous  but  interrupted  and  definitely  grouped. 

Goniops  chrysocoma  Os  ten  Sacken. — A North  American  species, 
known  from  not  very  frequent  captures,  from  New  York,  New 
Jersey,  Pennsylvania,  Ohio,  and  Maryland.  Taken  in  June  and 
July,  usually  on  foliage. 

Goniops  chrysocoma  (Plate  2,  Fig.  28)  is  the  only  representative  of 
the  Pangoniinae  of  which  we  know  anything  of  the  early  stages,  but 
in  this  species  our  knowledge  is  rather  complete  owing  to  the  obser- 
vations of  Walton  and  McAtee. 

Walton  was  the  first  to  observe  oviposition  accurately  and  to 
describe  the  egg.  However,  Walton  relates  that  the  first  fly  seen  by 
him  was  presented  to  him  by  Mr.  Warren  S.  Fisher,  of  Highspire,  Pa., 
who  took  a female  in  the  act  of  ovipositing  on  a leaf  of  what  proved 
to  be  Angelica  on  July  4,  1907,  near  Highspire.  The  plant  overhung 
a small  more  or  less  permanent  ditch  of  water,  and  it  was  naturally 
inferred  that  the  larva  might  be  aquatic  in  habit,  in  common  with 
others  of  the  family. 

However,  on  June  14,  1908,  while  collecting  on  a dry  hillside,  in  a 
brush  patch,  about  five  miles  to  the  eastward  of  the  former  locality, 
Walton  found  another  female  of  this  species  in  the  act  of  oviposition 
on  the  under  side  of  one  of  the  leaves  of  a small  oak  sapling,  to  which 
his  attention  had  been  attracted  by  a peculiar  buzzing  sound.  The 


58 


THE  EARLY  STAGES  OE  TABANID^E 


female  made  no  effort  to  escape,  indeed  it  required  considerable  force 
to  remove  the  insect  from  her  position  near  the  eggs.  The  immedi- 
ate locality  was  a hillside  pasture  lot,  half  covered  with  scrub  oak  and 
berry  bushes,  dotted  with  clumps  of  false  indigo.  The  nearest  water 
was  a small  overgrown  ditch  some  60  feet  distant. 

On  June  18  Walton  visited  the  same  spot  near  Highspire,  with  the 
hope  of  securing  additional  data,  and  was  rewarded  by  finding  another 
fly  in  a similar  position  on  a leaf  of  the  wild  cherry,  thirty  feet  dis- 
tant from  the  water. 

The  eggs  (Plate  2,  Figs.  28  to  32),  “ which  are  deposited  upon  the 
under  surfaces  of  the  leaves  of  various  herbaceous  plants  and  trees” 
(Walton),  in  a three-sided  pyramidal  heap,  are  described  by  him  as 
“ yellowish  white  in  color,  about  1.5  mm.  in  length,  slender,  slightly 
curved,  and  resembling  those  of  many  other  flies  in  general  appear- 
ance.” One  of  the  heaps  contained  534  eggs  by  actual  count  (Plate 
2,  Fig.  29). 

The  eggs  of  Goniops  have  been  further  observed,  according  to 
McAtee,  during  each  of  the  years  1908,  1909,  and  1910,  on  Plummer’s 
Island,  Maryland.  On  June  26,  1908,  Mr.  H.  S.  Barber  collected  a 
female  and  a large  greenish  white  egg  mass,  which  was  laid  on  the 
under  side  of  an  oak  leaf  about  8 feet  above  the  ground.  The  larvae 
hatched  June  28. 

In  1910  McAtee  found  four  egg  masses  on  July  3 and  two  on 
July  10.  One  of  the  first  four  egg  masses  was  collected.  The  larvae 
hatched  July  7.  Another  had  been  deserted  by  the  female  by  July 
10.  The  outer  layers  of  eggs  were  black,  and  from  these  issued,  on 
July  11,  numerous  proctotrupids,  which  Mr.  J.  C.  Crawford  says  are 
Telenomus , probably  an  undescribed  species.  The  two  remaining 
egg  masses  of  the  lot  found  July  3 were  covered  by  the  females 
until  July  10  (Plate  2,  Fig.  28),  a period  of  a week,  during  which 
time  many  eggs  were  added.  These  eggs,  and  the  two  masses  discov- 
ered on  July  10  as  well  (Plate  2,  Figs.  30  and  31),  were  hatched  by 
July  17.  They  were  deposited  on  the  under  sides  of  Eupatorium , 
Benzoin , and  Hamamelis  leaves.  Some  of  the  empty  egg  cases  (Plate 
2,  Fig.  32,  McAtee),  usually  clung  to  the  leaf  after  hatching,  but  in 
one  instance  not  the  slightest  trace  remained  of  an  egg  mass  on  a 


WERNER  MARCHAND 


59 


witch  hazel  leaf.  A fly  heard  by  Mr.  E.  A.  Schwarz  giving  its  pecu- 
liar buzz  on  July  13,  and  which  undoubtedly  was  ovipositing  then, 
was  located  by  McAtee  on  July  17.  On  July  24  the  female  was 
absent  and  the  eggs  were  hatching.  The  larvae,  dropping  to  the 
ground,  immediately  burrowed  in. 

These  observations  show  that  the  female  Goniops  guards  the  egg 
mass  sometimes  for  a week  at  least,  a fact  which  has  escaped  Wal- 
ton's attention;  that  this  precaution  does  not  always  prevent  para- 
sitism; that  the  period  of  incubation  varies;  and  that  the  larvae  are 
fitted  for  a subterranean  life  upon  which  they  enter  as  soon  as 
hatched. 

Walton  placed  the  two  batches  of  eggs  found  by  him  in  breeding 
jars  and  on  the  evening  of  July  25  the  first  larvae  made  their  appear- 
ance. The  second  lot  appeared  two  days  later.  The  eggs  are,  ac- 
cording to  him,  yellowish  white  when  deposited  and  change  but 
little  if  any  in  color  before  hatching.  The  process  of  hatching  was 
observed.  The  larvae  were  quite  lively  when  hatched  and  “it  was 
a curious  sight  to  see  them  come  tumbling  out  of  the  eggs  by  dozens 
when  the  cluster  was  brought  under  the  bright  light."  According 
to  him,  the  period  of  incubation  is  from  7 to  10  days. 

According  to  McAtee,  eggs  have  hatched  in  from  2 to  11  days 
from  the  date  of  collection.  But  from  the  fact  that  eggs  are  added 
to  the  mass  for  several  days,  and  that  all  hatch  at  the  same  time, 
it  must  be  inferred  that  the  eggs  within  the  body  of  the  female  keep 
pace  in  development  with  those  laid.  To  determine  the  true  period 
of  incubation  observations  must  cover  the  process  from  the  laying 
of  the  first  egg  to  hatching  (McAtee). 

All  the  egg  masses  found  on  Plummer's  Island  in  1910  (McAtee) 
were  on  the  steep  north  slope  of  the  principal  elevation  of  the  island, 
which  is  a well  shaded,  cool,  and  damp  locality.  The  finding  of 
seven  egg  masses  in  this  area  of  less  than  an  acre  in  one  season  shows 
that  Goniops  chrysocoma  is  not  uncommon  locally,  even  though  little 
is  known  of  it  and  recorded  captures  are  not  numerous  (McAtee). 

As  to  the  larval  stage,  I have  already  related  Walton’s  observa- 
tions on  the  hatching  process.  The  larvae  obtained  by  him  were 
divided  into  three  lots,  the  first  placed  in  earth  entirely  submerged 
in  water,  the  second  in  dampened  sand  without  food  of  any  kind,  the 


60 


THE  EARLY  STAGES  OF  TABANID^E 


third  in  a jar  of  damp  earth  together  with  some  small  angleworms. 
Twelve  hours  later  the  first  lot  were  all  dead;  both  of  the  other 
lots  were  lively  and  apparently  in  good  condition.  The  second  group 
continued  to  live  without  food  for  about  ten  days  and  then  died. 
The  remaining  group  lived  for  some  weeks  but  finally  died  also,  the 
angle  worms  being  alive  and  uninjured. 

Walton  concludes  that  the  larva  is  terrestrial  (as  confirmed  by 
McAtee)  and  the  period  of  incubation  is  from  seven  to  ten  days 
(see  above). 

The  young  larva  (Plate  7,  Fig.  93,  a , b,  c ) is  described  as  follows: 

“The  freshly  hatched  larva  is  slightly  more  than  2 mm.  in  length,  slender,  but 
capable  of  contracting  the  body  into  an  almost  spherical  mass;  in  color  it  is  pale 
yellowish  white,  semitranslucent.  The  head,  which  is  capable  of  being  entirely 
withdrawn  into  the  first  thoracic  segment,  bears  several  pairs  of  antenna-like 
appendages  and  an  obtusely  pointed  chitinous  hook.” 

“On  each  side  of  the  median  line  of  the  body,  within  the  second  thoracic  seg- 
ment, there  is  a distinct  pinkish  spot;  also  on  the  last  segment  there  is  a pair  of 
round  black  spots  resembling  stigmata  [Graber’s  organ  (?)];  elsewhere  the  body 
seems  to  be  absolutely  devoid  of  hairs  or  tubercles.” 

McAtee’s  description  of  the  larva  goes  much  more  into  detail. 
He  also  described  the  adult  larva  from  a specimen  collected  by  Mr. 
Theodore  Pergande,  and  the  pupa  collected  by  him.  In  fact  the 
greater  part  of  McAtee’s  article  is  devoted  to  the  description  of  the 
newly  hatched  and  full  grown  larva  and  pupa  of  this  species.  In  the 
description  of  the  larvae  the  segments  are  numbered  from  the  head 
backwards.  McAtee  does  not  accept  the  customary  use  of  the  terms 
pro-,  meso-,  and  metathorax  for  the  three  anterior  segments  of  the 
larvae,  but  speaks  of  them  as  the  first,  second,  and  third  body  segments, 
which  they  really  are.  In  the  newly  hatched  larvae  they  are  scarcely 
differentiated  from  the  following  segments.  In  the  full  grown  larvae, 
while  distinguishable  by  the  surface  markings,  their  exterior  features 
are  homologous  with  those  of  more  posterior  body  rings.  In  com- 
paring and  describing  them,  therefore,  it  is  more  natural  to  use 
numerical  designations.  McAtee’ s description  of  the  young  larva 
follows : 

“ First  Stage  Larvce. — The  average  length  of  first  stage  larvae  of  Goniops  chry - 
socoma  which  have  been  preserved  in  alcohol  is  about  1 mm.  In  life  they  are 


WERNER  MARCHAND 


61 


about  twice  as  long.  The  larvae  are  not  tuberculate,  but  the  margins  of  each 
segment  from  the  third  to  the  tenth,  especially  the  front  margins,  are  more  or  less 
raised  into  low  rounded  rings.  On  a larva  with  arched  body  definite  transverse 
impressions  behind  the  anterior  fleshy  annulus  of  each  segment  are  apparent 
under  magnification.  They  render  the  annuli  conspicuous  enough,  in  fact,  to 
give  an  impression  as  of  false  feet  to  the  naked  eye  observing  the  larvae  crawling.” 

“The  mouth  parts  are  exceedingly  minute  and  hard  to  observe.  In  arrange- 
ment they  suggest  those  of  the  full  grown  larva,  described  below,  and  the  homol- 
ogies have  been  made  out  accordingly,  and,  it  is  hoped,  successfully.  The 
drawing  [Plate  7,  Fig.  95,  a,  b]  is  strictly  diagrammatic  and  is  made  up  from  a 
number  of  studies  of  larval  heads,  none  of  which  showed  all  the  parts  in  the  posi- 
tion used  in  the  drawing.” 

“Labrum  ( Ibr .)  short,  pointed,  black-tipped,  and  slightly  curved  downward. 
Labium  triangular,  not  bifid  as  in  full-grown  larvae.  Maxillae  ( mx .)  fleshy, 
truncate-conical,  with  a short  downwardly  projecting  lobe  on  the  inner  side  of  the 
distal  end;  palpus  ( mxp .)  arising  from  the  end  of  the  maxilla,  first  joint  long, 
somewhat  enlarged  distally,  tipped  by  a number  of  short  rods  or  spines,  one  of 
which  is  larger  and  blunt.  It  may  be  considered  a second  palpal  joint  surrounded 
at  the  base  by  a group  of  spines.  Mandibles  ( md .)  fleshy,  blunt-tipped,  crenu- 
late  on  lower  edge,  lying  just  inside  of  maxillae.  Antennae  {ant.)  straight,  tapering, 
directed  forward;  basal  joint  as  long  as  first  palpal  joint,  somewhat  expanded  dis- 
tally, second  joint  double,  one  of  its  divisions  longer  and  apparently  tipped  with 
a seta.” 

“First  segment  of  body  slightly  inflated,  first  and  second  segments  convex 
above,  flattened  beneath,  lower  lateral  edge  rather  prominent.  Second  and 
third  segments  with  two  or  three  longitudinal  furrows  on  each  side.  Second  seg- 
ment with  two  conspicuous  well  separated  elongate  brownish  spots  visible  (ap- 
parently somewhat  under  the  surface)  on  the  dorsal  aspect.  Hind  margins  of 
segments  becoming  more  undulate  posteriorly,  markedly  so  on  ninth  and  tenth 
segments.  Last  segment  with  two  round  black  spots,  (spiracles)  Graber’s  organ 
(?),  set  close  together  on  the  median  dorsal  surface;  this  segment  with  two  more 
prominent  ventral  tubercles,  two  similar  lateral  ones,  and  other  minute  tubercles.” 

Both  Walton  and  McAtee  have  seen  the  organ  of  Graber  in  the 
young  larva  of  Goniops;  the  former  speaking  of  a resemblance  to 
spiracles,  while  the  latter  seems  frankly  to  believe  that  he  is  dealing 
with  spiracles.  For  a possible  derivation  of  this  organ  from  spiracles 
we  possess,  however,  no  evidence,  except  that  in  tabanid  larvae  all 
spiracles  except  the  terminal  ones  have  disappeared. 

Full  Grown  Larva  (Plate  7,  Figs.  92,  a , b,  c,  and  94). — The  full 
grown  larva  described  by  McAtee  is  one  of  two  collected  by  Theodore 
Pergande,  near  Cabin  John  Bridge,  Maryland,  April  13,  1899.  They 


62 


THE  EARLY  STAGES  OF  TABANIDiE 


were  found  under  stones  covering  the  opening  of  mouse  burrows. 
The  color  in  life  was  gray.  The  general  color  of  the  preserved 
specimens  was  dark  brown,  the  head  black.  The  total  length,  when 
the  head  was  retracted,  is  given  as  17  mm.,  the  greatest  diameter 
7.5  mm.  With  the  head  fully  drawn  out  the  larva  measures  21  mm. 
For  the  details  McA tee’s  description  is  quoted: 

“Head  convex  above,  flattened  beneath,  its  lower  lateral  edge  a well  marked 
ridge  made  by  the  stretching  of  the  skin  over  the  prolonged  basal  supports  of 
mouth  parts.  Anterior  part  of  head  marked  off  from  posterior  part  by  a band  of 
very  thin  wrinkled  skin ; anterior  fold  of  this  band  beginning  dorsally  just  in  front 
of  two  large  lateral  smooth  areas  containing  the  indefinite  bluish  white  eye  spots; 
fold  descending  obliquely  over  side  of  the  head,  ending  ventrally  between  bases 
of  maxillae.  Anterior  part  of  head  and  areas  surrounding  eye  spots,  with  glassy 
surface,  remainder  covered  with  thin  wrinkled  skin.’’ 

McAtee  describes  the  mouth-parts  in  detail  (Plate  7,  Fig.  95,  a,  b.) 

“Epistoma  and  labrum  (Ibr)  forming  a thin  lance-like  projection  between 
upper  parts  of  oral  apparatus.  Upper  edge  of  labrum  grooved  from  opposite 
middle  of  antennal  flap  (< anf .)  to  base  of  the  mandibles  ( md .) ; provided  with  an 
unequally  two-lobed  caruncle  just  back  of  the  upturned  tip  ( Ibr .).  Higher  lobe 
of  caruncle  and  tip  of  labrum  each  bearing  a solitary  anteriorly  directed  seta 
[see  Fig.  95,  a].  Lower  edge  of  labrum  applied  to  labium  (lb.);  latter  flat;  thin 
lateral  strips  diverging  from  a distinct  ramus  behind  being  chitinized,  the 
remainder  flexible.  Labium  ending  in  a pair  of  rounded  conical  fleshy  lips; 
flexible  portions  closely  set  with  short  yellow  hairs.” 

“Mandibles  black,  claw-like,  blunt,  sheathed  at  base  by  lobes  of  maxillae  (mx.). 
The  latter  thin,  flexible,  following  the  curve  of  the  mandibles;  their  slightly 
forward  curved  tips  surpassing  mandibles;  their  lower  edge  and  inner  side  pro- 
vided with  numerous  yellow  hairs.” 

“Palpi  ( mxp .)  arising  from  external  basal  flaps  of  maxillae.  First  palpal  joint 
inwardly  and  downwardly  curved,  second  setiform,  slightly  curved  downward 
and  overlapping  mandible.’ 

“Arising  in  the  arch  between  epistoma  and  side  of  the  head  is  a flap  (anf.) 
which  seems  to  be  part  of  the  antennal  apparatus.  It  follows  edge  of  epistoma 
nearly  to  base  of  mandibles,  and  curving  down  is  attached  to  the  posterior  third 
of  first  antennal  joint.  From  this  point  clear  around  the  curve  to  where  it  paral- 
lels the  epistoma  the  flap  is  fringed  with  long  yellow  hairs.  First  joint  of  antenna 
(ant.)  slightly  incurved  (thus  being  directed  outward),  nearly  three  times  as  long 
as  the  two  terminal  joints  together.  Second  joint  conical,  tapering  gradually, 
directed  forward  and  downward;  third  setiform  and  directed  downward.” 


WERNER  MARCHAND 


63 


“Anterior  part  of  first  segment  very  finely  tesselated,  the  granules  being 
arranged  in  irregular  longitudinal  rows.  The  head  retracts  into  the  posterior 
part  of  this  segment,  whose  exterior  is  a longitudinally  striate  thin  membrane 
inflated  to  gibbous  barrel  shape  [Plate  7,  Fig.  92].  The  line  of  separation  between 
the  parts  of  this  segment  is  marked  by  a ring  of  fine  fleshy  crenulations.  Second 
and  third  segments  surrounded  about  the  middle  by  undulate  crinkly  thin-edged 
folds  [Plate  7,  Fig.  92,  a,  b,  c]  with  five  symmetrically  placed  backward  angula- 
tions in  each  fold  on  each  side.  Parts  of  these  two  segments  posterior  to  the 
folds  with  as  many  longitudinal  sulci  as  there  are  angles  in  the  fold,  and  longitud- 
inally striate  with  fine  irregular  wavy  ridges.  Anterior  third  of  second  segment 
finely  striate  lengthwise.  Part  of  second  segment  just  in  front  of  fold  and  ante- 
rior portion  of  third  segment  granular.” 

“On  the  fourth  and  following  segments  these  folds  are  broken  up  into  series  of 
fleshy  tubercles,  on  both  sides  of  which  the  surface  of  the  segments  is  raised  into 
low  ridges,  which  on  the  anterior  segments  have  a few,  and  on  the  posterior  seg- 
ments several,  low  protuberances.  The  fourth  and  following  segments  more 
prominently  ridged  transversely  on  the  dorsal  area  and  longitudinally  on  the 
ventral  area.  A trace  of  longitudinal  striation  remains  on  posterior  of  three 
ridges  (on  each  segment  just  described)  or  protuberances  representing  it.  The 
fleshy  teeth  derived  from  the  medium  segmental  folds  largest  and  most  numerous 
on  the  middle  of  lateral  area  of  each  segment,  where  they  are  heaped  up  into 
irregular  elevations,  with  two  more  prominent  points  forming  a series  alongside; 
these  elevations  marked  off  by  deep  impressions  both  above  and  below  and  be- 
coming more  prominent  posteriorly.  There  are  three  tubercles  above  (supra- 
lateral  series)  lateral  prominences  and  about  five  below  (infralateral  series)  on 
each  segment  behind  the  fourth.” 

“The  fleshy  fold  is  continuous  across  the  dorsal  area  of  fourth  segment  [Plate 
7,  Fig.  92];  back  of  this,  dorsum  of  each  segment  marked  by  a depressed  compara- 
tively smooth  elliptic  area.  These  areas  bounded  in  front  by  a varying  number 
of  thin  fleshy  teeth  and  posteriorly  by  a series  of  low  broad  longitudinally  striate 
protuberances.  Two  of  the  latter  fall  into  a series  down  the  median  line  of  the 
segments,  on  the  ninth  and  tenth  of  which  they  become  closely  approximate, 
much  more  prominent,  and  round  pointed.  The  first  of  the  series  (supralateral) 
of  these  tubercles  above  the  prominent  lateral  elevations  bounds  the  dorsal  de- 
pressions at  the  sides  and  stand  in  a series  along  the  back.” 

“Ventral  series  [Plate  7,  Fig.  92]  of  protuberances  marked  off  from  infra- 
lateral series  by  a hiatus,  by  lower  and  thinner  teeth,  and  by  the  forward  arch- 
ing of  the  series.  It  consists  essentially  of  two  stronger  lateral  teeth  with  a 
varying  number  of  less  prominent  ones  between.  On  the  tenth  segment  the 
series  is  shortened  and  the  middle  elements  are  almost  lacking.  Between  these 
arched  series  of  teeth  and  posterior  ridges  on  the  ventral  surface  of  the  segments 
(which  are  represented  by  about  four  low  round  protuberances)  are  depressed 
areas  similar  to  those  of  the  dorsal  surface.  These  are  bounded  at  sides  by 


64 


THE  EARLY  STAGES  OF  TAB  ANTE)  iE 


first  protuberances  of  infralateral  series.  Each  segment  from  fourth  to  tenth 
has  a pair  of  impressed  dots  on  inner  pair  of  elevations  of  the  posterior  longitu- 
dinally striate  ridge.  Segments  six  to  nine  have  four  of  these  impressions,  one 
outside  of  each  of  the  median  pair.” 

“On  the  last  or  eleventh  segment  the  anus  is  a semicircle  with  the  convex  side 
downward,  overhung  by  four  prominent  tubercles  in  bilaterally  symmetrical 
pairs.  Mouth  of  the  air  tube  a smooth  oval  surface  just  above  the  anal  tubercles. 
It  has  a vertical  slit  and  is  surrounded  by  a projecting  crenulate  frill.” 

Pupa  (Plate  11,  Fig.  121,  a,  b,  c ). — One  of  the  full  grown  larvae 
collected  by  Mr.  Pergande  pupated  and  a female  imago  issued  May 
29,  1899.  McAtee’s  description  follows. 

“Length  of  the  pupal  shell  19  mm. ; greatest  diameter  6.5  mm.  Head  and  thorax 
of  the  pupa  a lighter,  abdomen  a darker  ferruginous.  Head  and  thorax  finely 
and  irregularly  wrinkled;  anterior  half  of  each  abdominal  segment  finely  wrinkled 
transversely,  posterior  half  with  wrinkles  less  distinct  or  absent  (especially  on 
ventral  surface),  but  very  finely  and  closely  punctuate.  This  makes  the  color 
appear  more  intense,  in  places  almost  orange.  Middle  of  the  segments,  except 
the  first,  surrounded  by  an  interrupted  fringe  of  definitely  grouped  sharp  pointed 
spines,  the  larger  of  which  tend  to  be  serrate.” 

“Vertex  of  head  marked  by  a narrow  rounded  longitudinally  wrinkled  trans- 
verse ridge.  In  the  depression  between  this  ridge  and  the  antennal  prominences 
and  in  front  of  the  extremities  of  the  ridge  are  two  outwardly  directed  setae. 
Antennal  sheaths  short,  appressed,  downwardly  curved,  conical,  arising  from 
two  low  wrinkly  protuberances  (the  antennal  prominences  above  mentioned). 
These  prominences  separated  by  a deep  fold,  and  from  them  curved  and  diverg- 
ing impressed  lines  run  down  the  face.  Below  each  antennal  sheath  is  a widely 
separated  vertical  pair  of  setae.” 

“Prothorax  longitudinally  wrinkled,  except  for  a smooth  area  behind  and 
below  each  antennal  sheath.  A setiferous  tubercle  stands  above  each  of  these 
smooth  areas.  Prothorax  angulate  in  the  median  line  behind.  Mesothorax 
three  times  as  long  as  the  prothorax,  bearing  two  spiracular  tubercles  near  an- 
terior lateral  angles  (about  opposite  the  middle  of  each  lateral  half  of  the  pro- 
thorax). These  tubercles  similar  to  those  described  below,  but  complicated  by 
flexures  of  the  walls.  They  bear  at  the  summit  upwardly  arched  crescent- 
shaped rimae  or  air  slits.  The  only  setae  I can  find  on  the  mesothorax  are  one  on 
each  side  directly  back  of  these  spiracular  tubercles.  Metathorax  very  short  in 
the  median  line,  but  somewhat  longer  at  the  sides,  which  have  two  rounded  angles 
anteriorly.  Wing  pads  and  leg  sheaths,  the  latter  slightly  the  longer,  almost 
covering  ventral  surface  of  the  first  abdominal  segment.” 

“Middle  of  each  side  of  first  to  seventh  abdominal  segments  with  elevated 
round  polished  knobs  bearing  on  the  posterior  portion  of  their  summits  the  pos- 


WERNER  MARCHAND 


65 


teriorly  arched  crescentic  spiracles.  Second  to  seventh  segments  with  a sharp 
pointed  backwardly  curved  spine  directly  posterior  to  each  spiracular  tubercle. 
A short  distance  above  this  spine  is  a similar  one,  and  between  these  two  from 
one  to  four  shorter  ones.  Some  shorter  teeth  occur  also  both  ventrally  and 
dorsally  from  the  stout  spines.  These  lateral  spines  become  stronger  poste- 
riorly.” 

“There  is  a definite  break  between  the  groups  of  lateral  spines  and  the  weak 
spines  forming  the  lateral  elements  of  the  dorsal  series.  This  break  is  marked  by 
sharply  impressed  lines  on  segments  2 to  7 [Plate  11,  Fig.  121].  Dorsal  series  of 
spines  on  second  to  seventh  segments  consisting  of  a pair  of  stout  spines  on  each 
side  of  the  median  line  [Plate  11,  Fig.  121],  the  pair  on  the  seventh  segment  being 
most  widely  separated.  On  each  side  of  the  mid-dorsal  pair  are  about  three 
other  symmetrically  placed  strong  spines.  Between  the  larger  spines  are  vary- 
ing numbers  of  shorter  ones,  and  gradually  diminishing  small  ones  terminate  the 
series  on  each  side.  All  spines  sharp  pointed  and  curved  backward.  Ventral 
surface  of  the  second  to  seventh  segments  with  smaller  spines,  having  median 
pairs  of  stronger  teeth,  most  widely  separated  on  the  third  segment  and  nearest 
together  on  the  seventh.  There  is  a tendency  for  one  of  the  minor  spines  on 
each  side  of  the  median  pair  to  be  larger  than  its  fellows.  These  smaller  spines 
of  varying  number  but  maintaining  their  series  across  venter  of  the  segments, 
interrupted  only  by  the  stronger  ones  and  diminishing  gradually  on  each  side. 
A wide  hiatus  exists  between  the  last  of  the  ventral  series  on  each  segment  and 
the  group  of  spines  near  the  spiracular  tubercle.  Eighth  or  terminal  segments 
with  three  strong  spines  on  each  side,  connected  by  series  of  weaker  points 
[Plate  11,  Fig.  121].  The  pair  made  by  the  uppermost  of  these  strong  lateral 
teeth  is  more  widely  separated  than  the  corresponding  ventral  pair.  In  each 
case  the  interspace  (that  is,  the  dorsal  and  the  ventral  area  of  the  segment)  is 
devoid  of  points,  except  for  small  ones  immediately  adjacent  to  the  large  spines. 
The  location  of  the  larval  anus  is  marked  by  a rounded  transversely  wrinkled 
knob  and  the  spiracular  eminence  consists  of  two  conspicuous  tuberculate  pro- 
jections surmounted  by  sharp  pointed  downwardly  curved  spurs.” 

This  is,  so  far,  the  longest  description  of  a tabanid  larva  and  pupa 
which  we  possess. 

Of  early  stages  of  the  many  exotic  Pangoniinae  nothing  appears  to 
be  known. 


HjEMATOPOTA,  early  stages  in  general. 


We  owe  to  Neave  notes  on  the  early  stages  of  this  genus.  He 
collected  at  Mt.  Mlanje  in  southern  Nyasaland,  Africa.  The  larvae 
were  by  no  means  easy  to  obtain  as  compared  with  those  of  Chrysops , 
a few  individuals  of  three  species  only  being  found  in  September  and 
October.  Later  in  the  season,  in  January,  considerable  numbers  of 
the  larvae  of  an  unidentified  species  were  obtained,  perhaps  those  of 
Hcematopota  insatiabilis  or  an  allied  species.  The  larvae  all  seem  to 
resemble  each  other  closely  and  it  is  very  difficult  to  distinguish 
specific  differences  in  them,  though  they  differ  in  a marked  manner 
from  those  of  any  other  genus  of  tabanids  seen  by  Neave.  The  dif- 
ferences between  these  larvae  and  those  of  Chrysops  are  discussed 
under  that  genus  (Plate  5,  Figs.  73  and  74).  The  limitation  of  the 
pigmented  areas  to  the  anal  segment  and  the  abruptly  truncated 
syphon  seem  to  be  characteristic  of  and  peculiar  to  this  genus,  as  also 
are  the  very  short,  sometimes  almost  invisible  pseudopodia. 

The  genus  Hcematopota  is  represented  by  a large  number  of  species 
in  the  Old  World,  especially  in  tropical  Africa;  the  species  are  less 
numerous  in  the  New  World  and  the  genus  is  entirely  absent  in 
Australia. 

Hcematopota  crudelis  Austen. — -An  African  species,  originally  de- 
scribed from  German  East  Africa,  and  by  Neave  found  by  no  means 
uncommon  near  Mt.  Mlanje,  in  southern  Nyasaland,  in  the  months  of 
October  and  November. 

The  first  larvae  of  Hcematopota  found  in  Africa,  by  Neave,  belonged 
to  this  species.  Several  of  the  larvae  were  found  in  September  and 
October,  and,  though  many  were  lost,  two  males  and  three  females 
eventually  emerged  in  October  and  November. 

The  larva,  which  is  figured  (Plate  6,  Fig.  85)  differs  from  that  of 
Hcematopota  insatiabilis  only  in  that  the  pigmented  areas  are  more 
pronounced  round  the  anus  and  at  the  base  of  the  syphon. 

The  pupal  aster  (Plate  13,  Fig.  170)  has  hooks  of  nearly  equal  length 
and  forms  a very  regular  star.  There  is  no  true  dorsolateral  comb, 
though  one  female  has  a minute  knob-like  process  in  place  of  it. 
The  pupal  aster  is  figured. 


66 


WERNER  MARCHAND 


67 


Hcematopota  decora  Walker. — An  African  species,  which  prefers 
low  and  dry  country,  therefore  not  common  in  the-Mlanje  district  of 
southern  Nyasaland,  where  Neave  made  his  studies.  However, 
Neave  has  acquainted  us  with  the  larval  and  pupal  stages. 

The  larva  was  of  the  usual  Hcematopota  type,  but  the  pigmented 
areas  on  the  anal  segment  were  an  orange  color.  This  might,  how- 
ever, have  been  due  to  the  mature  condition  of  the  larva,  which  was 
about  to  pupate.  The  pupal  aster  is  regular  in  shape.  A dorso- 
lateral comb  consisting  of  three  spines  is  present.  Pupal  aster  and 
dorsolateral  comb  of  a female  are  figured  (Plate  13,  Fig.  169,  a,  b). 

Hcematopota  insatiabilis  Austen. — An  African  species,  abundant 
near  Mt.  Mlanje,  southern  Nyasaland,  about  November  and  early 
December,  according  to  Neave  (1915). 

A few  larvae  of  Hcematopota  insatiabilis  were  obtained,  and  from 
some  of  these,  three  females  were  bred  between  November  7 and  10, 
1913.  The  three  posterior  segments  of  “what  is  believed  to  be  the. 
larva  of  this  species”  are  figured  (Plate  6,  Fig.  86).  There  seems  to  be 
no  pigmentation  except  a narrow  double  ring  at  the  posterior  end 
of  the  eleventh  segment.  The  circular  ridge  on  the  tenth  segment 
shows  no  pigmentation.  The  twelfth  segment  is  very  short  and 
rounded. 

The  pupa  is  figured  (Plate  11,  Fig.  131)  but  not  described.  The 
pupal  aster  of  this  species  (Plate  13,  Fig.  172,  a , b,  c ) is  very  remark- 
able, the  upper  hooks  being  reduced  to  mere  knobs,  while  the  middle 
pair  are  enormously  enlarged.  A well  marked  dorsolateral  comb 
is  present.  Pupal  aster  of  the  female  in  side  view  and  from  behind  is 
figured,  also  the  dorsolateral  comb. 

Hcematopota  pluvialis  Linne. — One  of  the  commonest  and  most 
widely  spread  tabanids  in  Europe,  known  also  to  torment  the  rein- 
deer in  Lapland,  where  it  occurs  in  incredible  numbers.  It  is  the 
representative  of  a genus  spread  all  over  the  world  but  absent  'in 
Australia,  while  in  Africa  it  is  represented  by  a large  number  of 
species. 

In  the  more  recent  literature  nothing  is  found  concerning  the  life 
history  of  this  species,  the  earlier  work  having  escaped  attention  of 
recent  investigators. 


68 


THE  EARLY  STAGES  OE  TABANID  .52 


Zetterstedt  believed  that  the  larvas  of  Hcematopota  live  in  the  dung 
(Scholtz). 

Scholtz  reported,  as  early  as  1850,  having  found  the  pupae  of  this 
species;  we  shall  give  his  statement  with  the  other  facts  available  on 
the  pupal  stage. 

Larva  and  pupa  of  this  species  have  subsequently  been  described 
by  three  authors,  independent  of  each  other.  All  agree  that  they  are 
terrestrial  in  habit. 

Brauer  (1883)  once  obtained  the  larva  of  Hcematopota  from  the  larva 
of  Helops  lanipes  (Coleoptera,  Tenebrionidae) , from  which  when  it 
seemed  to  be  in  process  of  molting,  the  tabanid  larva  came  to  light. 

Brauer  (1869)  is  the  first  to  give  accurate  descriptions  of  the 
early  stages  (Plate  6,  Fig.  83,  a-d),  with  the  exception,  however, 
of  the  egg  state,  which  remains  unknown  in  Hcematopota  pluvialisy 
while  it  has  been  observed  in  other  species  of  Hcematopota. 

Brauer  found,  in  an  excursion  made  in  June,  1869,  to  Lang  En- 
zersdorf,  Austria,  near  the  railroad  embankment,  in  a region  of  scat- 
tered cottonwood  ( Populus  alba ),  in  entirely  dry  soil,  a white  grub, 
about  20  mm.  in  length  and  3 to  4 mm.  in  diameter,  which  was  un- 
fortunately only  briefly  examined  with  a lens.  When  in  the  evening 
Brauer  began  to  examine  it  more  closely  the  grub  had  pupated,  and 
it  was  only  from  the  remainder  of  the  larval  skin  that  the  character 
of  the  larva  could  be  ascertained.  However,  the  description  obtained 
from  this  meager  material  is  very  accurate. 

The  larva  (Plate  6,  Figs.  83,  a , b,  84,  and  91)  is  cylindric,  twelve-segmented 
-(head  included).  The  head  (Plate  6,  Figs.  84  and  91)  is  formed  after  the  type  of 
tabanid  larvae,  almost  completely  differentiated,  the  chitinous  plates  diverging 
i behind  and  exceeded  in  length  by  two  long  rods  in  the  middle,  which  are  con- 
tinuous with  the  middle  chitinous  plate  of  the  head  and  with  the  labrum.  The 
latter  is  narrow,  somewhat  curved  downwards,  widened  at  the  tip,  and  ciliated 
laterally.  Close  to  the  sides  are  the  hooked,  downwardly  curved  parallel  man- 
dibles, their  margin  being  convex  and  serrate.  Below  the  mandibles  and  partly 
within  the  concavity  formed  by  them  are  the  maxillae,  which  are  soft  in  appear- 
ance. Their  basal  part  is  globular  and  slightly  spiny,  the  distal  part  is  formed 
by  a finger-like  piece;  at  the  side  of  the  latter,  externally,  a two-jointed  palpus  of 
twice  its  length,  the  two  joints  being  of  equal  length.  The  terminal  joint,  more- 
over, is  widened  and  excavated  to  spoon  shape.  Above  and  at  the  sides  of  the 
iinandibles  are  the  antennae,  of  which  the  distal  joints  are  cylindric  and  simple, 


WERNER  MARCHAND 


69 


the  first  one  thick  and  long,  the  second  short  and  narrow.  There  are  no  bristles 
at  the  base  of  the  antennae.  The  eye-spots  are  small,  perhaps  more  distinct  in 
life,  and  situated  behind  the  middle  of  the  head.  The  whole  head  is  deeply 
retractile.  The  body  is  pure  white  in  color  with  many  longitudinal  striae,  and 
bearing,  on  the  fourth  to  tenth  segments,  small  fleshy  warts  on  the  lateral  and 
ventral  sides,  each  segment  having  four.  These  warts  can  be  retracted,  giving 
the  larva  an  almost  smooth  appearance.  The  last  segment  ventrally  with  a 
thick  half  globular  anal  prominence,  and  posteriorly  with  a short  conical  structure 
with  a vertical  two-lipped  fissure.  The  lips  of  the  latter  are  strongly  chitinized, 
transversely  sulcated,  each  of  them  leading  to  one  of  the  main  tracheal  trunks; 
they  represent  the  posterior  spiracles  of  the  larva,  while  the  small  anterior 
spiracles  are  situated  on  the  posterior  half  of  the  second  segment. 

The  whole  structure  of  these  respiratory  organs  indicates  that  the 
larva  had  not  lived  in  water  or  left  it  only  for  pupation,  as,  according 
to  Brauer,  in  all  tabanid  larvae  of  terrestrial  habitat  the  posterior 
spiracles  are  analogous  in  structure,  while  the  aquatic  larvae  of  Ta- 
banus  autumnalis  and  Hexatoma  pellucens  are  enabled  to  extend  the 
last  segment  like  a telescope,  showing  a similar  fissure  only  at  the  end 
of  this  tube. 

A much  more  detailed  description  of  this  larva  is  given  by  Perris 
(1870),  who  found  it  twice,  and  each  time  in  a single  individual, 
in  the  decayed  wood  of  old  pine  stumps.  Of  the  two  specimens 
found  one  was  sacrificed  to  be  studied;  the  second  one  metamorphosed 
and  produced,  to  the  surprise  of  the  observer,  the  species  Hcematopota 
pluvialis.  This  fly,  as  he  says,  is  very  common  in  regions  of  France 
where  there  are  no  pines,  and  so  abundant  in  the  Landes  that  he 
could  not  have  missed  the  larvas  if  the  stumps  or  the  bark  of  dead 
trees  were  its  normal  place  of  development,  as  he  had  especially 
studied  all  insects  inhabiting  the  pine.  Consequently,  Perris  as- 
sumes that  the  insect  has  deviated  from  its  ordinary  habits.  How- 
ever, the  larvae  were  found  in  the  pine  wood  detritus  itself  where  they 
apparently  had  lived,  and  in  which  the  larva  mentioned  changed  to 
pupa  after  three  months. 

A translation  of  Perris’  description  of  the  larva  (Plate  6,  Fig.  82,  a-e ) 
is  given  below : 

Larva  (figured)  12  mm.  in  length.  Smooth,  hard,  leathery  (coriaceous),  cylin- 
dric,  attenuated  at  both  ends,  anteriorly  more  than  posteriorly,  very  finely  and 
densely  striated  in  a longitudinal  direction. 


70 


THE  EARLY  STAGES  OF  TABANID^E 


Under  ordinary  conditions  the  head,  which  is  small  in  comparison  with  the- 
body,  reddish  and  semicoriaceous,  appears  conical;  but  when  protruded  for- 
ward, it  forms  a sort  of  neck  posteriorly.  It  is  retractile  to  the  extent  that  it 
can  disappear  completely  in  the  first  segment.  The  front  is  protruded  into  a 
fleshy  mouthpiece  which  Perris  assumes  to  be  the  labrum.  To  the  right  and 
to  the  left  of  this  a black  horny  linear  piece  is  seen,  which  is  curved  anteriorly 
and  prolonged  posteriorly  into  a rod,  becoming  more  and  more  thinned  out,  which 
is  observed  through  the  transparent  tissues  and  which  is  inserted  deep  in  the 
first  segment.  These  two  rods  are  at  first  parallel,  then  somewhat  diverging. 
They  serve,  according  to  Perris,  as  places  of  attachment  to  the  muscles  which 
move  the  head  and  the  linear  piece  mentioned,  which  are  the  mandibles.  Below, 
two  fleshy  subconical  pieces  are  seen,  fused  together  at  their  base,  of  which  the 
inner  is  separated  from  the  outer  one  only  at  the  tip  of  the  latter.  The  external 
piece,  which  is  a maxilla,  is  surmounted  by  a rather  long  palpus  of  two  joints, 
the  first  of  these  joints  one  and  a half  times  as  long  as  the  second;  the  inner 
piece  is  the  lobe  of  the  maxilla.  Above,  on  each  side  of  the  head,  opposite  to  the 
base  of  the  maxillae,  a rather  long  antenna  is  situated,  which  appears  to  consist 
of  three  joints,  of  which  the  first  is  very  short,  the  second  four  or  five  times 
longer,  the  third  slender  and  about  one-half  as  long  as  the  preceding. 

This  larva  has,  consequently,  a protruded  labrum,  two  horny  serrate  man- 
dibles, two  maxillae  with  their  lobes,  two  maxillary  palpi  consisting  of  two  joints,, 
two  antennae  consisting  of  three  joints,  all  extending  beyond  the  head. 

The  body  is  formed  of  eleven  segments;  the  first,  or  prothorax,  truncated 
conical,  is  one  and  a half  times  as  long  as  all  the  other  thoracic  segments,  which 
are  slightly  shorter  than  the  abdominal  segments.  The  first  six  of  the  latter 
have  eight  fleshy  and  retractile  protuberances,  two  dorsal  ones  distant  from  one 
another,  two  on  each  side  placed  close  together,  and  two  ventral  ones  placed  at 
a distance  from  one  another  like  the  dorsal  ones.  These  protuberances  are  of 
great  help  to  the  larva  when  it  starts  to  walk.  In  this  act,  the  larva  presses 
the  head  against  the  surface  on  which  it  is  to  move  and  contracts  the  body,  at  the 
same  time  retracting  the  protuberances;  then,  freeing  the  head  and  exserting  the 
protuberances  which,  all  around,  exercise  a strong  pressure,  it  pushes  forward. 
The  last  segment  of  the  abdomen,  which  is  somewhat  rounded  at  the  sides,  is 
rather  suddenly  and  considerably  narrowed  down  posteriorly,  where  it  terminates, 
in  a disk  in  the  center  of  which  a reddish  vertical  slit  is  observed  with  the  aid 
of  a lens.  At  high  magnification  this  slit  is  recognized  to  be  a spiracle  the  lips  of 
which  are  transversely  striated.  In  seeking  for  the  remaining  respiratory  orifices, 
two  of  these  oval  and  reddish  spiracles  are  found  at  the  posterior  border  of  the 
prothoracic  segment,  one  on  each  side.  Under  the  last  segment,  in  its  anterior 
third,  there  exists  a fleshy  prominence,  of  the  shape  of  an  ellipsoid  placed  trans- 
versely, and  retractile;  it  is  traversed  by  a longitudinal  fissure  or  sulcus  which 
indicates  the  anus.  This  prominence  also  serves  to  aid  locomotion. 


WERNER  MARCHAND 


71 


The  body  of  the  larva  is  completely  covered,  except  in  the  anal  region,  with 
very  fine  and  densely  placed  longitudinal  striae  easily  seen  with  the  lens.  They 
certainly  play  a part  in  the  contractions  and  dilatations  of  the  body. 

The  larvae  of  this  species  have  been  found  and  described  again  by 
Beling  (1875).  ’ One  larva  was  obtained  by  him  on  March  24,  1873, 
from  hog  dung  which  had  been  collected  from  a meadow  and  piled 
up  at  the  edge.  This  larva  was  kept  in  a room  which  was  not  heated, 
and  pupated  on  June  24,  producing  a male  imago  on  July  6,  after  a 
resting  period  of  twelve  days.  From  December,  1873,  Beling  fre- 
quently found  single  larvae  in  the  soil  of  cultivated  fields,  several 
times  also  in  the  earth  of  hedges  bordering  on  meadows.  The  larvae 
which  were  collected  were  kept  in  a glass  jar  partly  filled  with  humus 
and  continued  to  live  for  months  in  this  medium,  without  injuring 
one  another.  However,  at  the  time  when  metamorphosis  was  to 
take  place,  they  killed  one  another,  apparently  for  the  purpose  of 
feeding  on  the  killed  individuals  by  sucking  out  their  contents,  and 
of  the  ten  larvae  finally  only  one  remained,  which  pupated  on  June 
25,  1874,  and  produced  a female  imago  on  July  5,  after  11  days  of 
pupal  condition. 

According  to  Beling,  the  larvae  resemble  closely  those  of  Tabanus 
bromius  in  color,  appearance,  and  habits,  but  are  at  once  distin- 
guished by  being  shorter  and  thinner,  and  by  the  much  finer  punc- 
tated12 longitudinal  striation.  Concerning  localities  of  capture, 
Beling  states  that  the  Hcematopota  larvae  occur  chiefly  in  humus  of 
cultivated  fields,  while  the  larvae  of  the  terrestrial  Tabanus  species 
mentioned  are  found  usually  in  grass-covered  or  meadow  soil. 
Beling ’s  description  of  the  larva  is  translated  below. 

Larva. — 10  to  12  mm.  in  length,  2.5  mm.  in  width,  somewhat  contractile;  when 
fully  extended,  up  to  15  mm.  and  even  more  in  length,  twelve-segmented,  pale 
yellow,  strongly  and  glassy  shining,  with  very  fine  irregular  (punctated)  longitu- 
dinal striation,  somewhat  narrowed  in  front  and  behind,  and  especially  during 
locomotion  narrowed  down  to  spindle  shape  in  the  anterior  part,  with  small 
narrow  brown  head  completely  retractile  into  the  first  segments,  appearing,  when 
seen  from  the  dorsal  side  of  the  first  two  segments,  as  a brown  longitudinal 
stripe,  broadened  behind  and  ending  in  two  points.  The  last  body  segment  is 
shorter  and  narrower  than  the  preceding  one,  rounded  at  the  posterior  border, 


12  The  German  word  used  is  “ N adelrissig.” 


72 


THE  EARLY  STAGES  OE  TABANJD2E 


with  a cushion-like  prominence  on  the  middle  of  the  rounded  part.  The  promi- 
nence is  often  in  the  shape  of  a short  thick  cylinder,  truncated  at  right  angles, 
bearing  in  the  middle  the  vertically  placed  stigmatal  fissure.  Anus  prominent 
on  the  under  side  of  the  last  segment.  On  the  under  side  of  the  fifth  to  the  elev- 
enth segments  inclusive  are  transverse  locomotor  swellings  near  the  anterior 
margin,  forming  six  longitudinal  rows,  of  which  four  on  the  ventral  side  are 
arranged  in  two  pairs,  not  far  distant  from  one  another,  while  in  the  outer  rows 
ridges  are  placed  at  a greater  distance  from  one  another  and  are  also  placed  farther 
back  from  the  anterior  segmental  border. 

Scholtz  (1850)  reports  having  found  the  pupae  of  this  species,  to- 
gether with  those  of  Tabanus  autumnalis  and  Tabanus  tropicus , on 
an  excursion  with  Prof,  von  Siebold  and  Dr.  von  Frantzius  in  the 
neighborhood  of  Breslau,  in  1850,  at  the  edge  of  a pond  which  was 
entirely  covered  with  Lenina , and  the  water  of  which  was  polluted 
from  manure  piles  surrounding  it.  Here  the  pupae  were  found 
quite  near  the  edge  under  a thick  moist  mass  of  decaying  Lemna} 
together  with  the  pupae  of  Stratiomys , Syrphus , etc. 

A translation  of  Brauer’s  description  (1869)  is  as  follows: 

The  pupa  (Plate  6,  Fig.  83,  c,  d)  15  mm.  in  length,  slender,  with  no  spines  at 
the  anterior  end,  bearing  here  only  two  small  tubercles.  The  wing  and  leg 
cases  do  not  extend  beyond  the  first  abdominal  segment;  the  second  to  tenth 
abdominal  segments  bear  a circular  armament  of  bristles,  the  last  segment  end- 
ing with  a thick  and.  only  slightly  diverging  fork  which  is  more  or  less  embedded 
in  the  cast  larval  skin. 

From  Brauer’s  pupa  there  appeared,  after  two  weeks,  a male  of 
the  species  in  question. 

More  precise  in  detail  is  the  description  given  by  Perris  (1870), 
obtained  from  the  cast  pupal  skin: 

The  pupa  (Plate  6,  Fig.  82,  /,  g)  presents  all  the  parts  of  the  perfect  insect. 
The  organs  of  the  head  can  be  guessed  rather  than  seen.  Two  frontal  tubercles 
(trouques),  surmounted  by  a bristle,  seem  to  be  the  cases  for  the  antennal  bases; 
two  other  oblique  tubercles  overlapping  with  their  borders,  in  the  region  of  the 
mouth,  seem  to  hide  the  palpi.  Between  these  two  tubercles  and  those  pre- 
ceding them  two  patterns  are  formed  by  small  elevated  lines,  the  upper  ones 
forming  a parenthesis,  and  the  lower  ones  a sort  of  brace.  Exterior  to  these 
patterns  there  exists,  on  both  sides,  a transversely  triangular  prominence,  with 
its  summit  overlapping  a little  the  border  of  the  head.  I (Perris)  consider  these 
prominences,  to  judge  from  their  location  and  form,  as  the  cases  for  the  distant 


WERNER  MARCHAND 


73 


division  of  the  antennae.  Below  there  are  two  small  tubercles  placed  obliquely 
one  below  the  other  and  surmounted  by  a little  hair,  and  on  the  vertex  four 
tubercles  arranged  transversely,  the  outer  ones  larger  and  bearing  a hair.  The 
dorsal  part  and  the  sides  of  the  thorax  bear  some  small  hairs.  The  abdomen, 
consisting  of  seven  segments,  presents  on  the  posterior  thirds  of  each  of  the 
first  six  a circular  series  of  stiff  bristles,  unequal  in  length,  thick  at  their  base 
and  directed  backwards.  The  last  segment  is  small  and  ends  in  a small  crown  of 
six  conical  diverging  teeth,  the  two  upper  ones  a little  smaller  than  the  others. 
Rather  near  the  anterior  border  of  the  thorax  two  obtuse  protuberances  are  seen, 
somewhat  more  excavated  and  striated  at  the  summit,  crossed  by  an  oblique  fur- 
row and  inside  showing  a depression,  the  thoracic  spiracles  of  the  nymph.  There 
are  also  visible  the  very  conspicuous  marks  of  six  abdominal  spiracles;  they  are 
situated  laterally  on  the  first  six  segments. 

It  is  conceivable  that  the  tubercles,  the  hairs,  and  the  bristles  with  which  this 
pupa  is  armed,  are  very  useful  when  it  wants  to  move  or  to  reach  the  open  air  in 
order  that  the  perfect  insect  should  not  be  hindered  in  the  act  of  eclosion.  In 
the  eclosion  the  shell  of  the  pupa  splits  all  along  the  median  and  dorsal  side  of 
the  thorax. 

Beling  also  describes  the  pupa  of  Hamatopota  pluvialis. 

Pupa. — 10  to  13  mm.  in  length,  about  2.2  mm.  in  width,  cylindrically  rounded, 
of  a dirty  brownish  yellow  color,  slightly  shining,  somewhat  narrowed  behind. 
Below  the  two  small  front  teeth  placed  beside  one  another,  and  above  the  frontal 
margin  two  small  tubercles,  not  much  farther  distant  from  one  another,  and 
each  bearing  a long  bristle.  Above  this  tubercle,  somewhat  distant  from  it,  is 
another  separate  hair,  and,  in  addition,  on  each  side  of  the  thorax  are  two  hairs, 
one  directly  located  behind  the  other.  Abdomen  nine-segmented,  first  segment 
very  short,  hardly  reaching  to  the  fourth  part  of  the  length  of  the  second  seg- 
ment; third  to  eighth  segments  inclusively  surrounded,  near  the  posterior  mar- 
gin, with  a circle  of  rather  densely  placed  brownish  bristle-shaped  teeth,  of  un- 
equal length,  appressed  backwards,  and  shorter  on  the  ventral  than  on  the  dorsal 
side.  Last  abdominal  segment  small,  bearing  in  the  middle  of  its  under  surface 
a row  of  similar  bristle-like  teeth  as  the  other  segments,  and  at  the  end  with  six 
outwardly  divergent  comparatively  strong  teeth  with  blackish  tips,  arranged  in 
a hexagon  of  which  the  upper  two  are  shorter  and  weaker  than  the  remaining 
ones. 

Hcematopota  sp. — Two  undetermined  species  of  Hcematopota  were 
observed  by  Patton  and  Cragg  (1913)  in  Madras,  to  oviposit,  as  all 
the  small  tabanids  observed  by  these  authors,  “on  blades  of  grass 
just  at  the  edge  of  a shallow  stream,  or  on  the  leaves  of  the  lotus 
plant  at  the  edges  of  small  ponds,  but  never  over  deep  water.” 


74 


THE  EARLY  STAGES  OF  TABANID^E 


These  species  of  Hcematopota  would  then  fall  under  the  heading 
of  those  larvae  which,  according  to  Patton  and  Cragg,  have  no  air 
sacs  and,  consequently,  perish  when  falling  into  deep  water.  Like 
the  other  small  species,  these  Hcematopota  “spread  out  their  eggs  in 
one  or  more  layers  on  blades  of  grass.”  The  eggs  of  one  species  of 
Hcematopota  are  dark  gray  when  deposited,  according  to  the  same 
authors.  No  descriptions  or  figures  are  given.  The  eggs  are  said 
to  be  torpedo-shaped  (not  cylindric)  in  all  the  smaller  tabanids  in 
Madras,  which  should  hold  good  for  Hcematopota. 

Hexatoma  pellucens  Linne. — A European  species,  according  to 
Schiner  common  in  Austria,  attacking  man  as  well  as  animals. 

In  the  middle  of  June,  1868,  in  a garden  in  Breitensee,  Austria, 
Ernst  Marno  found  in  a reservoir  8 feet  deep,  filled  with  rain  water 
and  dung  fluid,  together  with  larvae  of  Eristalis  and  Culex , some  dip- 
terous larvae  of  about  25  mm.  in  length,  which  were  on  the  dorsal 
side  beautifully  mottled  with  black.  Some  of  them  kept  in  this 
water  had  died  the  following  morning  and  were  preserved  in  alcohol. 
Brauer,  who  was  consulted,  pronounced  them  to  be  tabanid  larvae 
of  an  unknown  species. 

Early  in  July,  after  a heavy  rain,  larvae  were  again  found,  which 
in  color  and  appearance  seemed  to  be  the  same  species,  and  of  which 
in  the  middle  of  July  when  they  apparently  were  full  grown,  a consid- 
erable number  were  collected  from  the  mud  of  their  habitation. 

Of  these,  however,  many  perished  which  were  continually  replaced 
by  new  captures.  On  this  occasion  also  empty  pupal  cases  and  some 
full  ones  were  found;  the  latter  had  already  made  some  progress 
in  the  transformation  to  the  perfect  insect,  but  had  fallen  into  the 
water  and  had  soon  died  and  decayed. 

Brauer  determined  the  contents  of  these  pupae,  as  well  as  a dead 
fly  which  was  found  in  the  water,  as  belonging  to  Hexatoma.  However, 
a search  for  the  pupae  in  the  soil  surrounding  the  reservoir  was  in 
vain,  and  there  remained  sdme  doubt  as  to  the  identity  of  the  larvae 
and  pupae. 

The  larvae  captured  by  Marno  were  kept  by  him  in  a shallow 
flower  pot,  which  was  filled  half  with  moist  earth  and  half  with 
moist  decaying  foliage,  as  it  had  been  observed  that  the  larvae  ap- 


WERNER  MARCHAND 


75 


parently  showed  a preference  for  this  environment  and  had  been 
seen  to  work  their  way  into  a decaying  leaf.  They  did  well  under 
these  conditions;  only  a few  of  them  died,  and  on  July  22,  in  the 
afternoon,  the  first  soft  pupa  was  found,  the  larval  skin  still  adher- 
ing to  it,  and  identical  with  those  found  dead  in  the  water. 

A few  days  later,  when  a search  was  again  made  for  the  larvae, 
none  of  them  were  found,  but  instead  it  was  discovered  that  they 
pupated  in  the  interspaces  of  the  somewhat  defective  brick  walls  of 
the  reservoir,  and  here  some  pupae  as  well  as  larvae  were  collected, 
of  which  the  latter  were  more  or  less  contracted  in  preparation  for 
their  metamorphosis.  From  these  pupae  the  first  fly  was  obtained 
on  July  27,  in  the  morning. 

The  duration  of  the  larval  stage  is  about  three  weeks;  the  duration 
of  the  pupal  stage  Marno  could  not  ascertain,  leaving  his  material 
to  Brauer  to  study. 

The  larva  (Plate  6,  Figs.  89,  a,  b,  and  90,  a , b,  c ) has  been  de- 
scribed by  Brauer  (1883),  who  reports  it  to  be  aquatic,  being  found  in 
pools  and  puddles.  A translation  of  Brauer’ s description  is  given 
below. 

Larva,  when  extended,  slender  and  spindle-shaped;  when  contracted,  obtusely 
cylindric,  the  anterior  and  posterior  segments  being  retracted  in  the  latter  case. 
The  body  consists  of  a head  capsule  and  eleven  segments.  The  cuticle  has  a 
striped  appearance  because  of  the  many  closely  arranged  longitudinal  furrows. 
The  first  three  segments  and  the  under  surface  are  bone-white  (yellowish  white), 
the  dorsal  surface  of  the  remaining  segments  shows  beautiful  grayish  brown  pat- 
terns on  a white  background,  brought  about  by  microscopic  pubescence.  The 
head  capsule  (Plate  6,  Fig.  90,  a,  b,  c ) is  narrow,  formed  like  that  of  all  tabanid 
larvae,  compressed,  and  can  be  retracted  into  the  second  segment.  It  consists 
of  four  plates  which  posteriorly  are  not  connected,  and  of  which  the  two  middle 
ones  are  drawn  out  into  long  rods.  The  lateral  plates  show  on  half  their  length 
on  the  outside  an  irregularly  rounded  and  convex  eye-spot  on  each  side.  At  the 
anterior  end  is  a comb-like  upper  lip  reaching  above  and  between  the  mandibles. 
On  each  side  of  its  base  there  is  a cushion-like  projection  thickly  beset  with  mostly 
two-pointed  bristles,  on  which  the  antennae  are  inserted,  which  are  short  and  two- 
jointed.  The  first  joint  is  cylindric,  the  second  divided  lengthwise  into  two 
parts.  The  exterior  point  is  shorter  than  the  interior.  Below  and  to  the  inside 
of  the  antennae  are  the  hooked  and  more  strongly  chitinized  mandibles,  which 
may  be  moved  up  and  down  parallel  to  one  another.  Their  surface  is  trans- 
versely sulcate;  consequently  the  anterior  convex  margin  is  serrately  incised. 


76 


THE  EARLY  STAGES  OE  TABANIDiE 


Within  the  concavity  of  the  mandibles  the  softer  maxillae  are  placed.  The  ex- 
tremity of  the  latter,  curved  hook-like  in  the  same  way,  runs  parallel  with  the 
mandibles,  so  that  to  the  observer  from  the  side,  two  hooks  appear  superposed 
one  on  the  other.  The  maxillary  palpus  projects  obliquely  towards  the  outside 
and  above,  and  has  a thick  cylindric  basal  joint  and  a thinner  simple  terminal 
joint  of  double  length.  Beginning  with  the  third  body  segment,  there  appears  a 
short  intermediate  segment,  on  which  rather  long  bristly  hairs  are  inserted.  On 
the  ventral  side  several  circular  protuberances  with  bristles  are  noticed  on  the 
intermediate  segment.13  The  fourth  to  tenth  segments  show  on  the  dorsal  side 
two,  and  on  each  side  one  spinous  protuberance.  The  last  segment  has,  on  the 
ventral  side,  the  paired  anal  prominence,  covered  with  finer  and  stronger  hairs 
and  surrounded  by  a three-sided  furrow. 

At  the  basal  angles  of  the  anal  prominence  small  wart-like  swellings  appear. 
From  the  last  segment  a respiratory  tube  may  be  extended  which  is  rather  sharply 
pointed  and  narrowly  cone-shaped,  showing  at  the  tip  h,  vertical  fissure  between 
two  thickenings,  the  endings  of  the  main  tracheae  of  the  metapneustic  larva. 

The  pupa  is  a free  pupa,  and  is  found  in  the  ground. 

The  head  of  the  pupa  bears  on  each  side  above  the  base  of  the  antenna  a 
small  wart  with  a bristle,  and  above  and  below  the  antennal  sheath,  on  the  eyes, 
similar  but  slightly  smaller  warts.  B ehind  the  prothorax  are  the  anterior  spiracles, 
placed  on  small  cylindric  prominences  which  do  not  project  far.  The  wing  and 
leg  cases  reach  the  posterior  margin  of  the  first  abdominal  segment. 

Length  of  the  larva:  27  to  30  mm.;  width  in  the  middle  4 mm. 


13  The  German  word  used  here  is  “ Zwischenwulst”  which  means  a swelling: 
lying  between  the  segments. 


TABANUS,  EARLY  STAGES  IN  GENERAL. 

Much  that  can  be  said  about  Tabanus  in  general  has  been  said 
already  under  the  family  Tabanidae. 

The  eggs  of  Tabanus  are  not  appreciably  different  from  those  of 
Chrysops , except  that  the  latter  resemble,  according  to  Patton  and 
Cragg,  more  those  of  the  smaller  species  of  Tabanus , the  eggs  of  the 
larger  species  being  of  slightly  different  form.  According  to  Hart, 
the  eggs  of  Tabanus  are  always  laid  in  clusters  composed  of  several 
layers,  but  recent  observations  have  shown  that  from  this  rule  ex- 
ceptions are  frequently  met  with,  when  the  eggs  are  spread  out  in 
one  layer  or  even  loosely  scattered.  As  a rule,  however,  the  eggs  are 
laid  in  a cone-shaped  or  bilaterally  symmetrical  mass  containing 
several  layers  of  eggs  and  attached  to  various  objects  as  specified 
under  the  heading  of  Tabanidae. 

The  larvae  and  pupae,  studied  by  Hart,  form  two  groups,  which  may 
be  called  the  lineola  and  the  atratus  groups.  The  larvae  show  the 
most  distinctive  characteristics  in  the  structure  of  the  surface,  es- 
pecially of  the  prothorax,  which  has  lateral,  dorsal,  and  ventral 
shining  areas,  limited  in  front  by  an  opaque  pubescent  annulus. 
Comparing  the  anterior  extension  of  these  shining  areas,  Hart  found 
them  all  of  about  the  same  length  in  Chrysops  and  the  lineola  group 
of  Tabanus , although  this  length  varies  in  Chrysops . The  lateral 
prothoracic  areas  are  extensively  invaded  by  the  anterior  annulus  in 
the  atratus  group  of  larvae,  the  striated  shining  space  becoming  basal, 
being  not  more  than  half  as  long  as  the  dorsal  area.  The  upper 
lateral  space  of  the  mesothorax  is  not  closely  striate,  and  is  quite 
shining.  In  all  except  some  of  the  atratus  group  the  remaining  lat- 
eral striation,  including  that  of  the  prothorax,  is  not  much  finer,  and 
is  also  shining,  but  in  the  others,  as  in  atratus , the  prothoracic  and 
abdominal  lateral  striation  becomes  microscopically  fine  and  even 
subopaque.  A smooth  spot  near  the  lower  hind  angle  of  the  pro- 
thoracic lateral  area  furnishes  another  good  differential  character. 
The  dorsal  and  ventral  striation  varies  in  extent  according  to  age, 
but  the  thorax  is  striated  above  in  Chrysops , and  smooth  or  nearly 

77 


78 


THE  EARLY  STAGES  OF  TABANID^E 


so  in  Tabanus.  The  three  types  of  coloration  observed  are  well 
shown  by  the  three  Tabanus  larvae  figured  (Plate  3,  Figs.  40,  41, 
and  42). 

Pupa. — The  great  difference  between  the  abdominal  spiracles  and 
terminal  teeth  of  the  lineola  group  and  those  of  the  atratus  group  is 
evident  from  Hart’s  figures  (Plate  13,  Figs.  162  and  163).  In  both, 
the  thoracic  spiracles  are  in  a plane  nearly  parallel  to  the  adjacent 
surface  and  the  spinous  fringes  contain  long  and  short  spines.  The 
preanal  fringe  in  the  lineola  group  shows  more  or  less  of  a chitin- 
ous  web,  uniting  the  bases  of  the  spines. 

A pair  of  short  appressed  palpal  sheaths  on  the  lower  surface  of  the 
head,  resembling  the  antennal  sheaths,  differs  slightly  in  position  in 
related  species  of  the  atratus  group. 

The  species  of  Tabanus  have  been  classified  by  various  authors, 
but  for  convenience,  I have  listed  them  here  :n  alphabetical  order. 

We  possess  data  on  early  stages  of  fifty-five  determined,  and  four- 
teen undetermined  species  of  Tabanus.  Those  of  some  of  the  worst 
stock  pests  still  await  description. 

Tabanus  albimedius  Walker. — This  is  one  of  the  commonest  Indian 
species  of  T abanus , according  to  Patton  and  Cragg,  and  occurs  almost 
all  the  year  round  in  Madras. 

Observations  on  the  life  history  and  early  stages  have  been  made 
by  Patton  and  Cragg  (1913).  The  species  oviposits  in  a variety  of 
situations,  but  most  frequently  on  the  leaves  of  some  plant  over- 
hanging deep  water.  The  egg  masses  have  also  been  found  on  small 
rocks  in  the  bed  of  a stream,  and  on  pieces  of  string  hanging  over 
house  drains;  on  one  occasion  a mass  was  found  on  a papaya  tree,  at 
the  foot  of  which  water  was  occasionally  allowed  to  flow.  The  num- 
ber of  eggs  laid  is  between  500  and  600.  The  eggs,  as  in  all  the 
larger  Indian  species  mentioned  by  Patton  and  Cragg  ( Tabanus 
striatus , albimedius , and  speciosus)  are  subcylindric  with  tapering 
ends.  The  eggs  of  Tabanus  albimedius  measure  1.9  to  2 mm.  in 
length  and  4 mm.  in  breadth.  The  eggs  are  brownish  white  when 
deposited  A chalcid  parasite,  which  was  not  identified  by  Patton 
and  Cragg,  regularly  destroys  large  numbers  of  egg  masses  of  this 
species,  and  of  striatus.  This  species,  as  the  larger  species  of  India  in 


WERNER  MARCHAND 


79 


general,  oviposits  any  time  during  the  day,  but  as  a rule  in  the 
morning. 

When  “one  of  the  larger  species”  (including  Tabanus  albimedius ) is  about  to 
oviposit  “it  alights  on  the  leaf  or  blade  of  grass  with  its  head  downwards;  it  then 
thrusts  the  tip  of  the  abdomen  forwards  under  its  thorax,  and  deposits  an  egg, 
which  adheres  to  the  leaf  owing  to  the  sticky  substance  which  accompanies  it. 
The  abdomen  is  then  returned  to  its  original  position,  and  as  soon  as  the  next 
egg  is  ready  to  be  laid,  is  again  flexed,  and  the  second  egg  is  placed  at  one  or 
other  side  of  the  first.  In  this  way  three  or  four  eggs  are  laid  on  one  side  of 
the  first  and  three  or  four  on  the  other.  The  mass  at  this  stage  has  the  shape 
of  a V.  The  fly  now  moves  forwards,  and,  raising  the  end  of  the  abdomen  to 
one  arm  of  the  V,  places  a number  of  eggs  down  the  side  until  the  apex  is  reached; 
she  then  changes  over  to  the  other  side  and  deposits  eggs  all  down  that  arm  up 
to  the  apex.  In  the  end  a raised  compact  mass  of  eggs  is  built  up,  which,  if 
examined  with  a lens,  demonstrates  the  precision  with  which  the  eggs  are  placed 
in  reference  to  one  another.” 

The  larva  of  Tabanus  albimedius  has  not  been  described  and  also 
not  figured,  by  Patton  and  Cragg,  though  they  evidently  had  it 
under  observation.  A good  characterization  of  tabanid  larvae  in 
general  is  given,  but  the  differences  of  the  various  species  are  not 
entered  upon. 

Of  the  larva  of  this  species,  by  the  same  authors,  dissections  have 
also  been  made,  and  detailed  illustrations  are  given  of  the  mouth- 
parts  (Plate  7,  Fig.  97),  and  of  the  alimentary  tract  (Plate  7,  Fig.  98). 

The  figure  given  of  the  head  shows  the  mouth  appendages:  labrum, 
maxillary  palpus,  maxilla,  antenna,  and  mandible;  also  the  lateral 
area  of  spines  behind  the  antennae.  On  the  figure  the  antennae  appear 
to  be  two- join  ted,  while  the  authors  state  that  they  are  three- join  ted 
in  all  tabanids. 

The  figure  given  of  the  alimentary  tract  shows  the  esophagus, 
proventriculus,  the  narrow  salivary  glands,  apparently  inserted  in 
the  pharynx,  the  mid  gut,  hind  gut,  and  Malpighian  vessels,  four  in 
number. 

Patton  and  Cragg  were  the  first  to  publish  anything  on  the  ali- 
mentary tract  of  a tabanid  larva  based  on  dissection. 

Tabanus  atratus  Fabricius. — A species  inhabiting  eastern  North 
America,  as  far  west  as  Colorado,  conspicuous  by  its  large  size  and 


80 


THE  EARLY  STAGES  OE  TABANIDiE 


uniformly  black  color.  About  its  early  stages  we  are  informed  by 
Walsh,  C.  V.  Riley,  Hart,  and  Hine.  As  Hine  summarizes,  the  eggs 
are  deposited  around  marshy  places  on  grass  and  sedges,  and  the 
larvae  are  found  by  digging  in  the  mud. 

Hart  (1895)  is  the  first  to  give  notes  about  its  oviposition,  which 
was  noticed  in  Illinois,  in  July  and  August,  and  egg  masses  then  be- 
came frequent.  The  last  date  for  the  imago  was  August  15.  On 
August  11,  a female  was  observed  ovipositing  on  the  side  of  a wooden 
frame  standing  over  the  water.  The  egg  mass  was  placed  in  a breed- 
ing cage,  and  one  week  later,  on  the  18th,  many  larvae  hatched 
from  it.  Another  egg  mass  of  the  same  form  and  appearance,  placed 
on  the  dark  bark  of.  a stick  projecting  from  the  water,  was  brought 
in  July  27,  from  which  hatched  on  August  4 larvae  apparently  of 
this  species. 

Hart’s  description  of  the  egg  mass  and  egg  is  given  below: 

“Egg  Mass. — Blackish-brown,  subconic,  with  oval  base,  10-15  mm.  long 
and  8-10  mm.  wide,  height  5-7  mm.;  sides  convex  or  concave,  apex  correspond- 
ingly rounded  or  pointed;  eggs  pointing  obliquely  upward  and  towards  one 
end,  both  sides  meeting  upon  that  end  in  a more  or  less  prominent  longitu- 
dinal crest.  The  eggs  are  stacked  in  four  or  five  tiers,  one  above  another,  and 
gummed  together  into  a firm  mass.” 

“Egg. — Length  2.5-2. 7 mm.,  diameter  0.4  mm.  Dark  brown,  subcylindrical, 
ends  more  or  less  tapering  and  curved,  surface  minutely  rugose  and  subopaque.” 

Hine  completed  these  observations  in  1906.  According  to  him,  the 
eggs  of  T abanus  atratus  are  generally  placed  in  masses  of  various  sizes 
on  the  leaves  and  stems  of  grasses  and  sedges  and  other  plants  growing 
in  marshy  or  wet  ground,  but  not  necessarily  in  the  water.  A single 
mass  may  contain  as  many  as  500  eggs,  but  often  they  are  smaller 
and  they  may  be  larger;  they  are  white  when  first  placed,  but  soon 
turn  brownish.  The  mass  is  very  convex  and  composed  of  several 
layers,  one  above  the  other,  the  bottom  layer  being  attached  to  the 
surface  of  the  leaf  or  stem  and  the  other  layers  each  to  the  one  that 
was  placed  before  it.  Each  egg  is  elongate,  spindle-shaped,  between 
2 and  3 mm.  in  length,  and  narrowed  at  each  end.  A female  was 
observed,  in  Ohio,  ovipositing  on  June  23  at  11  o’clock.  The  eggs 
were  taken  and  kept  in  a room  out  of  the  sun,  where  they  hatched  on 
the  morning  of  July  2 before  6 o’clock,  thus  requiring  an  incubation 


WERNER  MARCHAND 


81 


period  of  nearly  nine  full  days.  It  has  been  proven  that  the  eggs 
of  tabanids  hatch  more  quickly  when  exposed  to  the  sun  during  the 
day  (see  Chrysops ),  where  they  are  usually  deposited;  therefore  the 
time  given  is  probably  too  long  for  eggs  under  natural  conditions. 

There  is  no  definite  way,  as  far  as  our  knowledge  goes,  according 
to  Hine,  of  telling  the  eggs  of  the  black  horse-fly  from  those  of  other 
species  of  this  genus,  but  being  a large  species  the  masses  are  much 
larger  than  in  some  others,  and  are  more  convex  than  usual.  The 
particular  place  of  oviposition  is  in  a measure  characteristic. 

It  is  of  interest  to  note  that  the  egg  masses  of  Tabanus  atratus  are 
often  found  to  be  parasitized. 

When  the  two  egg  masses  mentioned  and  described  by  Hart  had 
produced  larvae  they  were  placed  in  a dry  vial,  and  a little  later  it 
became  evident  that  both  masses  had  been  parasitized  by  Hymenop- 
tera,  minute  black  imagos  emerging  freely  in  the  vial.  An  exami- 
nation of  one  of  the  masses  showed  that  about  one-half  of  the  eggs 
had  been  infested.  Examples  of  the  imago  were  sent  to  Mr.  W.  H. 
Ashmead,  who  found  the  species  to  be  a new  one.  It  was  described 
by  him  as  Phanurus  tabanivorus  (Ashmead). 

I give  the  description  of  this  insect  at  the  end  of  the  chapter  on 
Tabanus , under  the  heading,  Parisites  of  the  early  stages  of  Tabanidae. 
The  illustration  of  this  insect,  given  by  Hart,  has  been  omitted. 

Hart  is  also  the  first  to  tell  us  about  the  early  larval  stages  of 
Tabanus  atratus.  From  the  two  egg  masses  he  obtained  larvae 
hatched  as  already  stated,  on  August  4 and  on  August  18.  In  the 
latter  case,  the  incubation  period  was  determined  to  be  one  week. 
The  larvae  were  at  this  time  commonly  found  in  water  among  the 
vegetation,  less  commonly  in  the  sand  of  the  shore,  and  young  indi- 
viduals became  frequent. 

Larva,  Newly  Hatched  (. According  to  Hart). — “In  this  stage  the  lateral  areas 
are  sculptured  similarly  to  those  of  the  adult,  but  the  dorsal  and  ventral  areas, 
though  shining,  are  rather  sparsely  striated.  Traces  of  the  dark  markings  are 
visible,  especially  on  the  posterior  segments.” 

According  to  Hine,  the  larvae,  when  first  hatched,  are  about  3 mm. 
in  length,  white,  and  with  a narrow  darker  shade  at  the  union  of 
each  two  segments.  As  soon  as  they  drop  to  the  ground  they  begin 


82 


THE  EARLY  STAGES  OF  TABANIDiE 


to  burrow  and  are  soon  beneath  the  surface,  where  they  cannot  be 
seen.  At  first  these  larvae  are  very  hard  to  see  on  account  of  their 
small  size;  consequently  not  much  has  been  learned  of  their  habits 
under  natural  conditions;  but  when  they  are  nearly  grown  they  are 
to  be  found  in  a variety  of  places.  We  now  come  to  a discussion  of 
the  adult  larval  stage. 

Walsh  (1863)  gives  a description  of  an  aquatic  Tabanus  larva  which 
he  was  unable  to  identify  as  the  imago  obtained  from  this  larva  was 
in  too  bad  a condition  to  be  identified,  having  remained  many  weeks 
without  care,  in  the  breeding  jar.  From  his  descriptions,  however, 
and  also  from  his  remarks  on  the  imago,  it  is  evident  that  the  larva 
belongs  to  Tabanus  atratus.  There  is  in  Massachusetts  no  other 
Tabanus  known  of  this  size  and  with  wholly  brownish  black  wings, 
and  the  description  of  the  larva  agrees  with  that  given  by  later 
authors  for  undoubted  Tabanus  atratus  larvae.  However,  some  of 
Walsh7  s smaller  specimens  may  belong  to  Tabanus  stygius  or  other 
species. 

Walsh  found  his  aquatic  larva,  on  many  different  occasions, 
“ amongst  floating  rejectamenta.77  On  one  occasion  he  found  six 
or  seven  specimens  in  the  interior  of  a floating  log,  so  soft  and  rotten 
that  it  could  be  cut  like  cheese.  Once  he  discovered  a single  speci- 
men under  a flat  submerged  stone,  in  a little  running  brook.  Finally, 
once  he  met  with  one  alive,  under  a log,  on  a piece  of  dry  land  which 
had  been  submerged  two  or  three  weeks  before,  whence  it  appears  that 
it  can  exist  a long  time  out  of  the  water.  Walsh  had,  on  several  pre- 
vious occasions,  failed  to  breed  this  larva  to  maturity,  and  the  only 
imago  he  had  was  obtained  in  1861  from  larvae  which,  suspecting 
them  to  be  carnivorous  from  the  very  varied  stations  in  which  they 
had  occurred,  he  had  supplied  with  a number  of  fresh  water  mollusks, 
but  the  habits  of  which,  in  consequence  of  having  been  away  from 
home,  he  was  unable  to  watch.  On  September  2,  1863,  he  found  a 
nearly  full  grown  larva  among  floating  rejectamenta,  and  between 
that  date  and  September  23  this  larva  devoured  “the  mollusks  of 
eleven  univalves77  (genus,  Planorbis ) from  one-half  to  three-fourths  of 
an  inch  in  diameter;  and  on  three  separate  occasions  observed  it  work 
its  way  into  the  mouth  of  the  shell.  In  this  operation  the  pseudopods 
were  energetically  employed  and  Walsh  found,  on  cracking  the  shells 


WERNER  MARCHAND 


83 


after  the  larva  had  withdrawn,  that  a small  portion  of  the  tail  end  of 
the  animal  was  left  untouched — no  doubt  in  consequence  of  his 
being  unable  to  penetrate  to  the  small  end  of  the  whorl  in  the  shell — 
and  also  the  skin  of  the  remaining  part  and  the  horny  tongue 
membrane. 

Walsh’s  description  of  the  larva  of  Tabanns  atratus,  including  that 
of  the  imago  which  serves  to  establish  its  identity  as  to  species,  is 
given  here: 

“ Tabanus  — ? Imago  male.  Blackish.  Legs  blackish,  wings  brownish  fuscous. 
Length  0.70  inch.  Expanse  1.30  inch.  One  decayed  specimen  came  out  between 
June  14  and  July  14,  1861,  from  a larva  found  early  in  June.” 

“ Larva,  from  the  living  specimens,  obtained  August  14,  1860,  and  September 
2,  1863.  Length  2.25  inches  when  extended,  1.75  inches  when  contracted;  di- 
ameter 0.25  to  0.30  inch.  The  specimens  found  in  1863,  0.25  inch  shorter. 
Body  cylindrical,  twelve-jointed,  the  three  or  four  terminal  joints  much  tapered 
at  each  side  of  the  body,  but  more  so  anteriorly  than  posteriorly,  and  joints  one 
and  eleven,  each  with  a retractile  membranous  prolongation  at  tip.  Joints  one 
to  ten  are  subequal;  eleven  is  about  two-thirds  as  long  as  ten,  and  twelve  about 
one-fourth  as  long,  and  0.5  inch  in  diameter.  Color  a transparent  greenish  white, 
paler  beneath,  on  the  anterior  and  posterior  margins  of  joints  two  to  eleven,  the 
anterior  annulus  laterally  connected  with  the  posterior  by  two  to  four  dark  green 
lines.  On  the  dorsum  of  four  to  nine,  and  more  obscurely  on  ten,  a dark  green 
basal  triangle,  extending  half  way  to  the  tip;  joint  one  with  paler  markings,  and 
with  no  dark  annulus  behind;  joint  twelve  entirely  fuscous.  Head  small,  appar- 
ently fleshy,  pale,  truncate-conical,  0.03  inch  wide,  and  about  0.04  inch  long  in 
repose,  inserted  in  joint  one  without  any  shoulder.  The  trophi  occupy  two- 
thirds  of  its  length,  but  it  has  a long  cylindrical  internal  prolongation,  extending, 
to  the  middle  of  joint  two,  which  is  sometimes  partially  exserted,  so  that  the  head 
becomes  twice  as  long  as  before.  All  the  trophi  are  pale  and  apparently  fleshy 
except  the  mandibles,  which  are  dark  colored  and  evidently  horny,  and  they 
have  no  perceptible  motion  in  the  living  insect.  The  labium  is  slender,  a little 
tapered,  and  three  times  as  long  as  wide,  on  each  side  of  and  beneath  which  is  a 
slender  thorn-like  decurved  brown-black  mandible.  The  labium  resembles, 
the  labrum,  but  is  shorter,  and  on  each  side  of  it  is  a slender  palpiform  but  exar- 
ticulate  maxilla,  extending  beyond  the  rest  of  the  mouth  in  an  oblique  direction. 
No  palpi.  On  the  vertex  are  a pair  of  short  fleshy  exarticulate  filiform  an- 
tennae, and  there  are  no  distinct  eyes  or  ocelli.  In  the  cast  larval  integument 
the  entire  head,  0.25  inch  long,  is  exserted,  and  is  dark  colored  and  evidently 
horny,  all  the  parts  retaining  their  shape  except  the  antennas,  labrum,  and 
labium.  The  whole  head  has  here  the  appearance  of  the  basal  part  of  the 
leaf  of  a grass  plant,  clasping  the  origin  of  the  maxillae  on  its  posterior  half,  and 


84 


THE  EARLY  STAGES  OF  TABANID^E 


bifurcating  into  the  somewhat  tapered  cylindrical  mandibles  on  its  anterior  half. 
The  maxillae  are  traceable  to  two-thirds  of  the  distance  from  the  tip  to  the  base 
of  the  head,  scarcely  tapering,  bent  obliquely  downward  at  two-thirds  of  the 
way  to  their  tip,  and  obliquely  truncate  at  tip.  On  the  anterior  margin  of  ven- 
tral segments  four  to  ten,  in  the  living  insect,  is  a row  of  six  large  fleshy  roundish 
tubercular  retractile  pseudopods,  the  outside  ones  projecting  laterally,  and  each 
at  tip  transversely  striate  and  armed  with  stout  bristly  pubescence;  on  the  ante- 
rior half  of  ventral  joint  eleven  is  a very  large,  transversely  oval,  fleshy,  whitish, 
retractile  proleg,  with  a deeply  impressed,  longitudinal  stria.  On  the  anterior 
margin  of  dorsal  joints  four  to  ten  is  a pair  of  smaller,  transversely  elongate,  re- 
tractile, fleshy  tubercles,  covering  nearly  their  entire  width,  armed  like  the 
pseudopods,  but  not  so  much  elevated  as  they  are.  No  appearance  of  any 
spiracles.  Anus  terminal,  vertically  slit,  with  a slender  retractile  thorn,  0.05 
inch  long,  visible  in  1860,  but  not  in  1863.  Head,  and  first  segment  or  two, 
retractile.” 

When  handled,  the  larva  is,  according  to  Walsh,  “ very  vigorous  and 
restless,”  and  burrows  with  great  strength  between  the  fingers,  and 
even  on  a smooth  table  walks  as  fast  as  any  ordinary  caterpillar, 
either  backwards  or  forward;  when  placed  in  a vessel  of  water  it 
swims  vigorously,  twice  the  length  of  its  body  at  every  stroke,  by 
curving  its  tail  around  laterally,  sometimes  to  the  right,  sometimes  to 
the  left,  so  as  to  touch  the  side  of  the  fourth  or  fifth  joint,  and  then 
suddenly  lashing  out  with  it.  In  such  a vessel  it  always  keeps  close 
to  the  surface,  and  at  the  end  of  every  stroke,  and  also  when  in  re- 
pose, elevates  the  anal  slit  out  of  the  water,  on  which  occasion  Walsh 
once  saw  a bubble  of  air  attached  to  it.  In  the  breeding  jar  the 
larva  scarcely  ever  comes  to  the  surface,  but  burrows  among  the 
decayed  wood,  aquatic  plants,  etc. 

The  larva  described  by  Walsh  differs,  according  to  him,  remarkably 
from  the  one  described  by  Degeer  ( Tabanus  bovinus  L.),  in  having 
ventral  pseudopods  as  well  as  dorsal  ones.  Walsh  says  that  it  might 
be  supposed  that  the  dorsal  tubercles  were  branchial,  “but  for  the  fact 
that  they  are  found  in  the  earth  inhabiting  species  described  by  De- 
geer/7 and  that  like  the  aquatic  larvae  of  Prionoxyphon  discoideus 
Say  (Coleoptera)  it  has  a branchial  apparatus  issuing  from  the  anus, 
and  the  short  retractile  anal  thorn,  observed  in  1860,  was  the  form 
assumed  by  this  structure  when  out  of  the  water.  This  assumption 
by  Walsh  is  partly  confirmed  in  so  far  as  the  terminal  spine  con- 


WERNER  MARCHAND 


85 


tains  the  openings  of  the  tracheal  trunks.  On  the  other  hand,  this 
spine  has  no  connection  with  the  anus,  which  is  not  terminal,  as 
Walsh  assumes,  but  lies  in  the  fleshy  tubercle  of  the  eleventh  seg- 
ment, where  Walsh  observed  “a  deeply  impressed,  longitudinal  stria.” 

The  larva  described  by  Walsh  and  which  undoubtedly  was  Tabanus 
atratus,  at  least  that  specimen  from  which  he  obtained  an  imago,  is 
found  according  to  him  from  the  beginning  of  June  to  the  beginning 
of  September,  at  which  latter  time  he  also  met  with  a specimen  only 
half  the  length  of  the  full  grown  specimen  (possibly  belonging  to  a 
different  species). 

The  pupa  has  also  been  described  by  Walsh,  and  the  description  is 
given  here  without  change: 

“The  pupa  (from  the  pupal  integument)  is  cylindrical,  suddenly  rounded  at  the 
head,  and  tapering  a little  in  the  last  two  abdominal  joints;  the  color  is  a very 
pale,  semitransparent,  yellowish  brown.  The  mouth  is  represented  by  six  tu- 
bercles, hexagonally  arranged,  above  which,  upon  each  side,  is  a trigonate  three- 
or  four-jointed  antenna,  pointing  outwards.  The  pronotum  commences  immedi- 
ately behind  the  antennae  and  bears  on  its  anterior  dorsal  submargin  a pair  of 
reniform  tubercular  spiracles,  the  mesonotum,  to  which  the  wing  cases  are  at- 
tached, is  twice  as  long  as  the  pronotum,  and  bears  on  its  anterior  dorsal  margin 
a pair  of  obliquely  placed  reniform  tubercular  spiracles,  three  times  as  long  as 
the  prothoracic  ones.  Then  follows  a very  short  metanotal  piece,  about  one- 
seventh  as  long  as  the  pronotum,  bearing  no  spiracle,  which  is  succeeded  by 
eight  subequal  segments,  all  but  the  last  bearing  on  their  lateral  dorsal  surface  a 
subbasal  round  tubercular  spiracle.  The  first  of  these  eight  segments  is  simple 
and  extends  to  the  tip  of  the  wing  cases;14  the  others  are  all  furnished  two-thirds 
of  the  way  to  their  tips  with  an  annulus  of  appressed  bristles  directed  back- 
wards. The  anal  thorn  is  very  robust,  having  a diameter  of  one-half  the  last 
abdominal  segment,  and  is  squarely  truncate  as  soon  as  its  length  is  half  its  width, 
and  terminates  in  six  small  robust  thorns,  arranged  in  a regular  hexagon.  Length 
0.97  inch;  greatest  diameter  0.21  inch.  One  specimen.” 

The  second  author  to  describe  the  larva  of  Tabanus  atratus  was 
C.  V.  Riley  (1870).  His  description  of  the  larva  is  quoted  by  Salmon 
and  Stiles.15 

14  “I  believe  this  first  spiracle-bearing  segment  to  be  metanotal,  as  also  the 
corresponding  piece  in  the  pupa  of  Midas  fulvipes,  u.  v.,”  (Walsh). 

15  Salmon  and  Stiles,  Emergency  report  on  surra,  pp.  100  and  101. 


86 


THE  EARLY  STAGES  OF  TABANIDiE 


“The  larva  [Plate  3,  Fig.  46]  is  a large  twelve-jointed  cylindrical  affair,  taper- 
ing at  each  end,  of  a transparent,  highly  polished,  glassy,  yellowish  or  greenish 
appearance,  shaded  with  bluish  green  and  furnished  above  and  below  as  in  the 
figure  (figure  given  by  Riley)  with  large  roundish  sponge-like  tubercles  which 
are  retracted  or  exserted  at  the  will  of  the  insect.  Though  the  external  integu- 
ment is  so  transparent  that  the  internal  structure  is  readily  visible,  yet  this 
integument  is  firm  and  the  larva  most  vigorous  and  active,  burrowing  with  great 
strength  either  backward  or  forward  in  the  earth  and  between  one’s  fingers  when 
it  is  being  held.  Placed  in  water  it  will  swim  vigorously  by  suddenly  curling 
round  and  lashing  out  its  tail,  but  it  is  apparently  not  as  much  at  home  in  this 
element  as  in  the  moist  earth,  for  it  is  restless  and  remains  near  the  surface  with 
the  tip  of  its  tail  elevated  into  the  air.  When  the  water  is  foul  it  moves  about 
actively  near  the  surface,  but  when  it  is  fresh  it  remains  more  quietly  at  the 
bottom.” 

This  specimen,  which  Riley  succeeded  in  breeding,  was  sent  to 
him  by  Mr.  Adolph  Engelmann,  of  Shiloh,  St.  Clair  County,  111. 
It  was  found  by  Mr.  William  Cooper,  of  the  same  county,  about  ten 
feet  from  a small  but  permanent  body  of  water.  Mr.  Cooper  at  first 
took  it  to  be  a leech,  but  when  he  attempted  to  catch  it  it  immediately 
commenced  burrowing  into  the  ground. 

The  larva  is  declared  by  Riley  to  be  semiaquatic,  for  it  is  at  home 
either  in  moist  earth  or  water.  This  specimen  was  kept  for  over  two 
weeks  in  a large  earthen  jar  of  moist  earth  well  supplied  with  earth- 
worms. It  manifested  no  desire  to  come  to  the  surface.  Riley 
found  several  pale  dead  worms  in  this  jar,  though  not  able  to  say 
positively  whether  they  had  been  killed  and  sucked  by  this  larva. 

Hart  (1895)  reports  that  he  has  taken  the  larva  of  Tab  anus  atratus 
in  every  month  of  the  season  except  June,  at  which  time  they  had 
mostly  reached  the  pupa  or  imago  stage.  They  seemed  to  prefer 
the  sandy  shores,  and  were  taken  abundantly  May  17  at  Hart’s 
Survey  Station  C,  by  running  through  a coarse  sieve  the  surface 
layers  of  sand  of  the  shore  near  the  wave-washed  margin.  Station 
C is  characterized  by  Hart  as  being  located  near  the  outlet  of  Quiver 
Lake,  the  shores  being  here  near  together  and  sheltered.  The  east 
bank  was  sandy,  with  a muddy  coating  over  the  part  which  is  exposed 
at  low  water,  while  the  west  shore  was  of  black  mud  grown  over  with 
willow  trees  and  overflowed  in  moderately  high  water.  The  water 
was  clear  and  on  both  sides  thickly  filled  in  summer  with  algae  and 


WERNER  MARCHAND 


87 


other  aquatic  plants,  having  little  or  no  current  in  ordinary  stages. 
The  same  process  of  sifting  was  repeated  June  25,  and  not  a single 
larva  was  found.  Individuals  placed  in  breeding  cages  failed  to 
transform.  A pupa  was  collected  June  30,  from  which  the  imago  ap- 
peared July  17.  A cast  pupal  skin  was  also  picked  up  July  18.  Sev- 
eral imagos  were  taken  in  the  same  locality  between  May  23  and 
June  22. 

During  the  winter  good  sized  larvse  sometimes  occurred  in  dip-net 
collections,  and  March  18  they  were  again  found  to  be  common  at 
Hart’s  Station  C,  in  loose  drifts,  partly  frozen,  left  by  an  early  spring 
rise.  The  previous  year  they  were  common  in  April  far  from  the 
margin,  among  sticks,  logs,  and  other  drift,  marking  the  higher  stage 
reached  by  the  water  on  March  19  of  that  year.  These  situations 
remained  moist  for  a long  time,  harboring  a large  variety  of  aquatic 
forms,  some  of  which  completed  their  transformations  successfully 
while  others  apparently  failed,  the  river  remaining  low  and  the 
weather  dry. 

Hart’s  description  of  the  mature  larva  (Plate  3,  Fig.  41)  is  as 
follows : 

“Larva,  Mature. — Length  45-55  mm.,  diameter  6-7  mm.  Transparent 
whitish  with  a greenish  tint,  marked  with  conspicuous  dark  brownish  or  greenish 
fuscous,  paler  in  younger  specimens.” 

“Lateral  prothoracic  striated  areas  less  than  half  as  long  as  the  dorsal,  stria- 
tion  microscopically  fine  and  opaque  or  scarcely  shining,  a small  smooth  spot  on 
the  anterior  margin  of  the  striated  area,  resting  on  the  lower  lateral  line;  remain- 
ing upper  lateral  areas  of  thorax  much  more  coarsely  and  sparsely  striate  and 
shining;  middle  and  lower  thoracic  areas — often  much  reduced,  or  even  entirely 
covered  by  the  lateral  stripes — with  distinctly  finer  and  closer  striation,  but 
still  shining;  abdominal  lateral  areas  with  still  finer  striation,  nearly  as  fine  as 
that  of  the  prothorax  and  feebly  shining;  dorsal  and  ventral  areas  all  smooth 
and  shining,  rarely  a few  broken  striae  about  their  margins,  at  the  base  of  the 
prothorax  or  on  the  anal  segment.” 

“Dark  annuli  distinct,  broad,  including  false  feet,  transverse  pale  spot  imme- 
diately in  front  of  dorsal  tubercles  narrow  or  closed  up  in  the  mature  larva;  on 
the  abdomen  above,  each  annulus  usually  extends  back  on  the  median  line  in  a 
triangular  prolongation,  often  nearly  attaining  the  next  annulus,  less  developed 
in  younger  larvae.  Prothoracic  lateral  space  occupied  in  front  of  the  striated  area 
by  a dark  opaque  quadrate  spot,  extending  from  the  anterior  annulus.  Lateral 
stripes  of  meso-  and  metathorax  broad,  at  least  the  upper  ones  widened  poste- 


88 


THE  EARLY  STAGES  OF  TABANID^E 


riorly,  the  lateral  edges  of  the  dorsal  areas  therefore  parallel  behind  the  middle 
of  the  segment,  as  seen  from  above;  lateral  stripes  of  abdomen,  especially  the 
intermediate  ones,  more  or  less  abbreviated  and  broken  up  posteriorly  except  on 
the  segment  next  the  last.  In  these  stripes  the  punctures  of  the  upper  and 
lower  rows  are  indicated  by  rounded  pale  dots,  and  those  of  the  inner  rows  by 
elongate  dots.  Last  segment  with  broad  dark  annuli  about  base  of  respiratory 
tube  and  around  anal  prominence,  with  lateral  connections;  also  more  or  less 
invaded  above  by  the  basal  annulus,  often  leaving  there  only  a pair  of  pale  spots 
posteriorly.  Often  a dark  spot  in  the  anterior  angles  of  the  ventral  space  on  the 
seventh  abdominal,  and  one  behind  the  anal  dark  ring.” 

“False  feet  moderately  elevated,  with  coarse  whitish  pubescence  more  or  less 
tipped  with  fuscous  or  with  brownish  in  younger  larvae,  dorsal  pair  narrowly  con- 
nected over  median  line.  Main  internal  tracheae  usually  subparallel,  sinuated, 
not  very  conspicuous,  although  easily  traceable.  Stigmatal  spine  rarely  visible.” 

A few  larvae  have  been  obtained  by  Hart,  which  are  like  atratus 
except  in  one  particular — the  surface  of  the  body,  especially  of  the 
anterior  abdominal  segments,  shows  a fine  undulate  wrinkling  re- 
sembling the  sculpture  of  the  pupa,  but  smoother.  As  the  specimens 
showing  this  appearance  were  shrunken  and  in  bad  condition,  it  is 
surmised  that  it  is  an  effect  of  letting  the  alcohol  get  too  weak  and 
then  changing  to  strong  alcohol. 

Hine  has  taken  the  larvae  while  digging  in  the  ground  in  the  vicinity 
of  ponds,  from  under  stones  on  ditch  banks,  from  the  water  with 
dip-nets,  and  occasionally  in  most  unexpected  places.  He  says, 
however : 

“If  one  is  looking  for  them  he  is  likely  to  meet  with  more  or  less  disappoint- 
ment, as  the  finding  of  one  specimen  does  not  indicate  necessarily  that  others 
may  be  taken  under  the  same  conditions.  The  fact  that  specimens  have  been 
taken  from  floating  logs  and  debris  suggests  that  they  may  be  transported  for 
longer  or  shorter  distances  in  this  way,  and  during  high  water  be  stranded  upon 
ground  which,  when  the  flood  subsides,  is  high  and  dry  and  far  removed  from  the 
bed  of  the  stream.  Since  the  species  in  all  its  habits  is  closely  associated  with 
water  and  wet  ground,  this  seems  to  be  the  only  way  of  explaining  the  appear- 
ance of  larvae  in  dry  soil  and  in  places  remote  from  where  the  eggs  are  laid.” 

Hine’s  description  of  the  larva  follows,  being  in  many  ways  more 
brief  and  accurate  than  that  of  Walsh  given  previously: 

“Full  grown  larva  nearly  2 inches  in  length.  General  color  yellowish  white, 
with  wide  dark  brown  bands  at  the  union  of  each  two  segments.  Prothoracic 
segment  on  each  side  with  two  lateral  grooves,  which  do  not  quite ; reach  the 


WERNER  MARCHAND 


89 


posterior  border  of  the  segment,  and  a dorsal  (?)  groove  continued  for  the  entire 
length.  These  grooves  and  a number  of  irregular  dots  on  the  posterior  part  are 
dark  colored,  while  the  remainder  of  the  segment  is  light.  Mesothoracic  segment, 
on  each  side,  with  four  longitudinal  grooves,  which  reach  nearly  the  entire  length. 
The  dark  markings  on  this  segment  include  a narrow  anterior  border,  the  lateral 
grooves,  and  a number  of  irregular  dots  near  the  posterior  margin.  The  meta- 
thoracic  segment  is  like  the  last  except  that  the  dark  color  on  the  anterior  mar- 
gin is  wider  and  the  posterior,  instead  of  being  dotted,  is  uniformly  brown.  The 
abdominal  segments  are  each  similar  to  the  metathoracic,  but  the  dark  mark- 
ings in  the  region  of  the  lateral  grooves  are  more  or  less  abbreviated.  Last  ab- 
dominal segment  with  two  pairs  of  dark  markings;  the  ventral  pair  extend  the 
whole  length  of  the  segment  and  are  connected  just  behind  the  anal  prominence 
by  a cross-band;  the  dorsal  pair  are  oblong,  somewhat  irregular  in  outline,  and 
extend  from  the  anterior  margin  to  beyond  the  middle  of  the  length.  At  the  an- 
terior ventral  border  of  each  of  the  first  seven  abdominal  segments  is  a trans- 
verse series  of  prolegs,  three  on  either  side  of  the  midventral  line.  These  pro- 
legs, are  located  within  the  dark  transverse  bands,  but  are  lighter  in  color  than 
these  and  prominent  enough  to  be  seen  easily.  Above  the  prolegs  on  either  side 
of  the  middorsal  line  is  a small  swelling  which  appears  as  a rudimentary  proleg; 
before  the  two  is  a distinct  transverse  light  spot  still  within  the  dark  area.” 

“The  head  of  the  larva  is  very  small  for  so  large  an  insect  and  the  mouth 
parts  are  minute.  The  mandibles  consist  of  two  strongly  chitinized  pieces,  and 
work  by  being  pushed  endwise  backward  and  forward.  When  drawn  in,  the 
anterior  ends  point  directly  forward,  but  when  protruded,  these  same  ends  point 
downward  and  backward,  thus  forming  a pair  of  hooks  by  means  of  which  the 
prey  is  held.  The  larva  is  able  to  protrude  its  mandibles  very  quickly  and  to  use 
them  very  effectively  on  soft-bodied  invertebrates  on  which  it  is  known  to  feed.” 

W.  A.  Riley  and  Johannsen  (1915)  have  also  figured  the  full  grown 
larva  of  Tabanus  atratus  (Plate  3,  Fig.  45),  and  Malloch  (1917)  fig- 
ures the  head  and  first  segment  of  the  larva  (Plate  5,  Fig.  77). 

On  the  pupal  stage  we  have  information,  in  addition  to  Walsh’s 
description,  by  C.  V.  Riley,  Hart,  and  Hine. 

Riley  reports  that  his  larva  transformed  to  pupa  within  the  ground 
during  the  early  part  of  July;  it  remained  in  this  state  but  a few  days 
and  the  fly  issued  July  13,  and  soon  made  its  presence  known  by  its 
loud  buzzing  inside  the  jar.  It  was  a perfect  specimen,  and  the 
pupal  integument  was  sufficiently  firm  and  polished  so  that  by  care- 
fully washing  off  the  earth  an  excellent  cabinet  specimen  was  ob- 
tained, which  retained  almost  the  exact  form  and  appearance  of  a 
living  pupa.  Before  the  escape  of  the  fly,  which  was  effected  through 


90 


THE  EARLY  STAGES  OF  TABANID^E 


a longitudinal  fissure  on  the  back  of  the  head  and  thorax,  reminding 
one  of  the  mode  of  escape  of  the  harvest  flies  {Cicada),  this  pupa  by 
means  of  the  horns  with  which  it  is  furnished  had  pushed  itself  up 
to  the  surface  of  the  earth. 

The  pupa  itself  (Plate  12,  Fig.  140)  is,  according  to  Riley,  nearly 
an  inch  and  a quarter  in  length  and  a third  of  an  inch  in  diameter. 
It  is  cylindric,  slightly  curved,  as  in  the  figure,  rounded  at  the  head 
and  tapering  at  the  extreme  hind  portion.  The  abdominal  seg- 
ments are,  all  but  the  first  one,  provided  with  a ring  of  fine  yellow 
bristles,  pointed  backwards.  There  is  a stout  thorn  at  the  anal  ex- 
tremity, bearing  six  other  thorns. 

The  pupa  state  lasts  but  a few  days  and  before  the  emergence  of 
the  fly  the  pupa  is  pushed  to  the  surface  of  the  ground  by  means  of  the 
bristles  and  thorns  of  the  abdomen,  with  bending  movements  of  the 
body. 

It  splits  along  the  dorsal  line  and  the  fly  emerges,  leaving  the  pupa 
case  in  perfect  condition. 

Hart’s  description  of  the  pupa  (Plate  13,  Fig.  163)  contains  some 
additional  details. 

“Pupa,  Male. — Length  30-35  mm.,  diameter  7.5  mm.  Yellowish  fuscous 
with  a brownish  tint,  thorax  not  paler.  Palpal  sheaths  distinct,  short,  very 
narrowly  separated  by  a depressed  space.  Abdomen  roughly  wrinkled  and  sub- 
opaque. Spiny  fringes  tipped  and  annulated  with  black.  Otherwise  as  in  the 
pupa  (female)  of  T.  stygius”  (described  by  Hart  in  the  same  paper). 

Hine  (1906)  gives  another  description  of  the  pupa: 

“Pupa  [Plate  11,  Fig.  124;  Plate  13,  Fig.  164]  about  II  inches  in  length. 
Color  brownish  yellow.  Antennal  and  other  tubercles  of  the  head  darker  than 
the  surrounding  parts.  Prothoracic  spiracle  slightly  elevated,  clear  brown  in 
color,  reniform  and  oblique,  rima  gradually  curved  to  near  the  dorsal  end,  where 
a distinct  hook  is  formed  by  a sharp  bend.  Abdominal  spiracles  nearly  round; 
rima  of  the  first  short  and  gradually  curved  and  with  a slight  hook  at  the  dorsal 
end.  Terminal  teeth  [Plate  13,  Fig.  164]  arranged  in  pairs,  a ventral  pair  and  a 
pair  on  each  side  formed  by  a dorsal  and  a lateral  tooth.  The  distances  between 
these  teeth  are  variable;  the  two  dorsal  are  nearest  together,  then  follows  the 
distance  between  a dorsal  and  a lateral,  the  distance  between  the  two  ventral, 
while  the  distance  between  a ventral  and  a lateral  on  each  side  is  greatest  of 
any.” 


WERNER  MARCHAND 


91 


This  appears  to  be  all  that  is  known  about  the  early  stages  of 
Tabanus  atratus. 

Tabanus  atrimcmus  Loew. — An  African  species,  common  near  Mt. 
Mlanje  in  southern  Nyasaland,  having  a preference  for  the  neighbor- 
hood of  wooded  streams,  and  being  there  most  abundant  in  Novem- 
ber and  December. 

Neave  collected  and  bred  the  larvae.  On  October  25  a number  of 
larvae  were  taken  in  the  Ruo  River  among  the  roots  of  grasses  in 
running  water,  but  occasional  individuals  were  also  found  in  the 
mud  in  other  wooded  streams.  Imagos,  bred  from  these,  began  to 
emerge  on  November  25.  At  the  same  spot  in  the  Ruo  River  some 
other  larvae  were  found  which  may  be  those  of  Tabanus  pertinens , 
but  they  were  not  bred  to  the  adult  stage. 

The  larvae,  which  are  figured  (Plate  3,  Fig.  52)  are  strikingly  dis- 
tinct from  those  of  the  apparently  closely  allied  Tabanus  variabilis 
Lw.  They  are  of  a somewhat  opaque  yellowish  color,  with  rather 
faint  brown  pigmented  areas.  The  pseudopodia  are  well  devel- 
oped, as  is  the  case  with  other  species  found  in  running  water,  and 
there  are  well  marked  hairs  on  the  syphon.  Though  invisible  in 
preserved  specimens,  two  pseudopodia  of  considerable  length  are 
present  immediately  anterior  to  the  anus. 

The  pupa  is  a clear  orange-yellow  color  and  the  aster  is  remark- 
able for  the  erectness  and  large  size  of  the  dorsal  pair  of  hooks, 
especially  in  the  female.  The  dorsolateral  comb  consists  of  a few 
widely  spread  spines. 

The  larva  (Plate  3,  Fig.  52),  the  pupal  aster  of  both  sexes,  and  the 
dorsolateral  comb  of  the  female  are  figured  (Plate  14,  Fig.  173,  a , b,  c). 

Tabanus  autumnalis  Linne. — Scholtz  (1850)  reports  finding  the 
pupae  of  this  species,  which  is  common  in  Europe,  with  those  of 
Tabanus  tropicus  and  Hcematopota  pluvialis  (see  also  these  species), 
on  an  excursion  in  the  neighborhood  of  Breslau  in  June,  1850,  at  the 
edge  of  a pond  covered  with  Lenina,  the  water  of  which  was  com- 
pletely polluted  from  manure  piles  surrounding  it.  The  pupae,  of 
which  the  flies  emerged  after  a few  days,  were  found  quite  near  the 
edge  under  a thick  moist  mass  of  decaying  Lemna , together  with 
Stratiomys  and  Syrphus  pupae. 


92 


THE  EARLY  STAGES  OF  TABANID^E 


The  larvae  were  first  found  in  1851,  by  Brauer  and  Goszy,  on  the 
shores  and  shallow  places  of  the  “ Wienfluss”  (Danube  ?);  also  the 
pupae  were  found.  Kollar,  1854,  gives  only  these  few  remarks  on 
the  subject. 

Raillet  says  (quoted  from  Brumpt) : The  larva  of  this  species  lives 
in  the  water;  it  breathes  the  air  at  the  surface  of  the  water,  like  the 
larvae  of  mosquitoes;  they  may  be  destroyed  likewise  by  spreading 
kerosene  oil  on  the  swamps  where  they  occur. 

It  is  possible  that  the  larvae  in  which  Graber  discovered  the  organ 
named  after  him  were  of  this  species  (Paoli). 

Surcouf  and  Ricardo  (1909)  report  on  their  observation  of  an  egg 
mass  of  Tabanus  autumnalis  L.  at  Lamballe  (Cotes-du-Nord)  in 
August,  1907.  The  eggs  formed  a dense  mass  attached  to  a reed, 
and  the  female,  turning  the  head  towards  the  moist  ground,  re- 
mained immobile,  making  no  effort  to  escape  when  it  was  captured. 
Unfortunately,  the  observers  waited  until  the  following  morning  to 
take  the  plant  with  its  roots,  and  in  the  meantime  the  grass  had 
been  cut. 

Graber  (1882)  gives  the  illustration  of  a newly  hatched  larva  of 
Tabanus , which  is  supposed  to  belong  to  Tabanus  autumnalis  (Plate 
8,  Fig.  99).  In  this  larva  Graber  studied  the  chordotonal  organs, 
tactile  bristles,  and  other  microscopical  details  (Plate  8,  Figs.  99  to 
102).  These  details  are  discussed  in  the  chapter  on  Tab anidae,  descrip- 
tion of  early  stages  (see  also  Tabanus  sp.  Nos.  10  and  12,  page  179). 

Tabanus  autumnalis  (Plate  8,  Figs.  99  to  102;  Plate  9,  Figs.  103  to 
108)  is  the  species  in  which  the  organ  of  Graber  was  probably  dis- 
covered for  the  first  time.  Krauss  (1879)  informs  us  that  Brauer,  in 
the  spring  of  1875,  demonstrated  in  his  entomological  class  the  larvae 
of  Tabanus  autumnalis,  which  had  been  bred  from  eggs,  and  called 
attention  to  a peculiar  and  undescribed  organ  in  the  abdomen. 
Drawings  of  the  organ  were  made  by  Krauss  but  not  published; 
according  to  the  latter,  they  agree  so  completely  with  those  pub- 
lished by  Graber  that  it  is  likely  that  Graber’ s “ Fliegenmade”  was 
in  fact  the  larva  of  Tabanus  autumnalis. 

Krauss  adds  the  statement  that  the  larvae  of  this  species,  in  contrast 
to  tabanids — the  larvae  of  which  live  in  damp  localities,  manure, 
decaying  plant  material,  or  in  the  ground — spend  all  their  develop- 


WERNER  MARCHAND 


93 


ment  in  the  water,  leaving  it  only  for  pupation,  which  takes  place 
at  the  edge  of  ponds,  in  the  mud,  among  plant  detritus,  etc. 

Krauss  expresses  the  opinion  that  the  organ  will  doubtless  also  be 
found  in  the  imago,  and  in  that  case  the  mystery  surrounding  it  may 
be  cleared  up. 

Von  Friedenfels  (1880)  reports  on  a larva  which  he  found  in  the  salt 
lakes  of  Siebenbiirgen.  This  larva  was  aquatic  and  transparent  and 
was  first  thought  to  be  an  annelid.  When  sent  to  Brauer  in  Vienna, 
it  was  identified  by  the  latter  as  a larva  of  Tabanus  autumnalis. 

Tabanus  bicallosus  Ricardo. — A smaller  species  of  Tabanus , recorded 
from  Pusa,  Bengal,  and  Madras,  by  Patton  and  Cragg,  to  whom  we 
also  owe  some  notes  on  its  early  stages. 

As  in  all  the  small  species  observed  by  these  authors,  the  eggs  are 
laid  on  blades  of  grass  just  at  the  edge  of  a shallow  stream,  or  on  the 
leaves  of  the  lotus  plant  at  the  edges  of  small  ponds,  but  never  over 
deep  water. 

The  eggs,  as  in  all  the  smaller  species  in  Madras,  are  torpedo-shaped, 
the  eggs  of  this  species  measuring  1.1  mm.  in  length  and  0.2  mm.  in 
breadth.  Figures  of  the  eggs  are  given  (Plate  1,  Figs.  12  and  13). 

The  egg  mass  figured  by  Patton  and  Cragg  seems  to  consist  of  two 
layers  spread  out  one  over  the  other,  and  the  whole  “ moulded  into 
the  hollow  of  the  blade  right  up  to  the  tip”  (as  in  other  small  Indian 
tabanids) . 

The  mature  larva  of  Tabanus  bicallosus  is  figured  by  the  authors 
(Plate  4,  Fig.  62),  but  no  description  is  given.  On  the  drawing  the 
eleventh  and  twelfth  segments  appear  to  be  completely  fused  (?), 
dorsal  pseudopods  are  well  developed,  which  should  indicate  an 
aquatic  mode  of  life.  There  seems  to  be  a color  pattern  similar  to 
that  of  the  larva  of  Tabanus  atratus. 

The  pupa  is  likewise  figured  (Plate  11,  Fig.  135),  but  not  described. 
In  addition,  figures  are  given  of  the  abdominal  tip  of  male  and  fe- 
male pupae  (Plate  12,  Figs.  144  and  145),  showing  the  arrangement  of 
the  six  terminal  teeth.  In  the  made  pupa  attention  is  called  to  the 
ribbed  anal  tubercle  and  the  continuous  fringe  of  spines  in  front  of 
it,  as  differing  from  the  condition  in  the  female,  which  has  a simple 
anal  tubercle  and  an  interrupted  fringe  of  spines  in  front  of  it. 


94 


THE  EARLY  STAGES  OF  TABANIDiE 


This  is  the  first  and  only  attempt  to  separate  the  sexes  of  tabanids 
in  the  pupal  stage. 

Tabanus  biguttatus  Wiedemann. — The  early  stages  of  this  species, 
which  is  widely  spread  throughout  Africa,  occurring  from  the  Cape 
to  the  Egyptian  Sudan,  have  been  described  by  King  (1908). 

The  eggs,  which  were  obtained  in  the  vicinity  of  Taufikia,  Sudan, 
in  the  marshes,  are  deposited  in  a rounded  mass  (Plate  1,  Fig.  18) 
on  grass  and  reeds  overhanging  a pool.  One  egg  mass  that  was 
counted  contained  about  450  eggs.  The  entire  act  of  oviposition  was 
not  timed,  but  it  lasted  well  over  half  an  hour.  When  a female  is 
ovipositing,  although  usually  exceedingly  shy,  the  stem  on  which  she 
is  resting  may  be  plucked  and  carried  away  or  put  into  a bottle  with- 
out disturbing  her.  Having  deposited  the  eggs,  she  covers  the  mass 
with  a creamy  white  secretion  which  turns  black  after  a short  time. 

The  egg  is  spindle-shaped,  slightly  more  pointed  at  one  end  than 
at  the  other,  and  white  in  color.  Length  2.5  mm.  The  eggs  under 
observation  hatched  in  about  eight  days,  but  possibly  under  natural 
conditions,  exposed  to  the  sun,  the  incubation  period  would  be 
shorter.  On  hatching,  the  larvae  fell  into  the  water,  swam  to  the 
sides,  and  buried  themselves  in  the  mud. 

The  larvae  can  swim  only  on  the  surface  of  the  water,  and  progress 
either  by  a telescopic  movement  or  by  lashing  vigorously  from  side 
to  side. 

Several  methods  of  rearing  them  were  tried.  The  majority  were 
placed  in  a large  glass  vessel  containing  mud,  living  grass,  and  water. 
Some  were  put  into  jars  containing  only  water,  others  in  dishes  con- 
taining moist  sand,  others  again  in  vessels  containing  sand  and 
water  so  arranged  that  there  was  a pool  at  one  end  of  the  vessel  and 
moist  sand  at  the  other. 

The  larvae  in  the  vessel  containing  mud,  grass,  and  water  did  well, 
but  many  were  devoured  by  predacious  insects — e.g.,  dragon-fly 
larvae — introduced  by  accident  in  the  mud  and  water,  and  others 
perished  owing  to  the  grass  dying  and  fouling  the  water  during 
transit.  Eventually  sand  and  water  in  Petri  dishes  were  found  to  be 
best,  as  it  could  be  kept  clean  and  the  larvae  easily  located  when 
wanted. 


WERNER  MARCH AND 


95 


At  first  they  were  fed  on  tiny  crustaceans  dredged  from  rain  pools, 
but  during  transit,  when  these  could  not  be  obtained,  scraps  of 
freshly  killed  raw  meat  and  congealed  blood  from  the  bodies  of 
gorged  mosquitoes  were  substituted.  After  arriving  in  Khartoum 
their  diet  consisted  of  earthworms,  as  a plentiful  supply  of  these 
could  always  be  procured. 

They  grew  very  slowly  and  at  greatly  varying  rates.  Two  larvae 
hatched  from  one  egg  batch  on  June  11  measured  respectively,  five 
weeks  later,  4 mm.  and  15  mm.  Owing  to  their  telescopic  nature 
it  was  exceedingly  difficult  to  measure  them  accurately,  so  the  figure 
must  be  taken  as  merely  approximate.  They  did  not  appear  to  be 
cannibalistic  in  their  habits,  as  several  of  various  sizes  were  reared 
in  the  same  dish  and  sometimes  kept  short  of  food,  but  were  never 
seen  to  attack  each  other.  When  one  died,  however,  its  comrades 
usually  devoured  it.  When  not  feeding  they  spent  most  of  their 
time  buried  in  the  sand,  with  just  the  tips  of  their  respiratory  syphons 
showing.  If  the  sand  was  allowed  to  dry  they  became  very  restless, 
and  would  make  continual  efforts  to  escape  from  their  jars  until 
water  was  given  them  again. 

Early  in  August,  when  they  were  about  eight  weeks  old,  they  ceased 
feeding  and  were  then  transferred  to  jars  containing  sand  to  a depth 
of  6 cm.  They  descended  to  the  bottom  of  these  jars  and  were  still 
there  when,  about  six  weeks  later,  the  author  went  to  England  on 
leave. 

On  January  28  King  returned  to  Khartoum,  and  it  was  found  that 
the  jars  then  contained  several  dead  adults — all  males — a few  dead 
pupae  and  larvae,  and  a single  live  larva.  This  last  died  early  in 
February  without  having  reached  the  pupal  stage.  The  empty  pupal 
cases  were  all  sticking  up  out  of  the  sand,  the  pupae  having  evidently 
worked  their  way  up  from  the  bottom  of  the  jars  by  means  of  their 
abdominal  spines.  In  several  instances  the  old  larval  skin  had 
remained  attached  to  the  caudal  teeth  of  the  pupal  case. 

Neave  (1915)  also  found  the  larvae  of  this  species  in  the  valley  of  the 
lower  Shire  and  its  tributary,  the  Mwanza,  in  southern  Nyasaland. 
Here,  in  the  sand  and  mud  on  the  banks  of  the  rivers,  large  num- 
bers of  larvae  were  obtained,  of  which  the  majority  belonged  to  this 
species,  and  these  were  chiefly  found  in  mud  among  the  Phragmites 


96 


THE  EARLY  STAGES  OF  TABANIDiE 


reeds  on  the  banks  and  in  the  back-waters,  etc.,  of  the  Shire  River. 
They  often  occurred,  especially  if  the  mud  was  inclined  to  be  dry, 
at  a depth  of  as  much  as  6 or  8 inches.  The  locality  figured  by 
Neave  represents  a large  flat  sand  bank  partly  covered  with  Phrag- 
mites,  at  the  border  of  a river  about  50  feet  in  width. 

The  lower  part  of  the  Mwanza  River  was  dried  up  at  the  time  of 
Neave’ s visit,  except  for  a few  isolated  pools,  on  the  banks  of  which 
many  larvae  of  Tabanus  biguttatus  were  found  in  the  mud.  Many 
others  were  subsequently  found  in  the  Ruo  valley  in  November. 

The  larva  is,  according  to  Neave,  of  a type  which  has  many  repre- 
sentatives, being  of  a clear  white  color,  except  in  individuals  about  to 
pupate,  with  well  defined  pigmented  bands  and  spots  between  the 
segments  and  on  the  anal  segment  (Plate  5,  Fig.  69).  Several  species 
have  larvae  of  this  type,  only  varying  in  the  amount  of  pigment  and 
in  the  distribution  of  it  on  the  anal  segment. 

King’s  description  of  larva  and  pupa  follows: 

The  larva  (Plate  5,  Fig.  75,  a,  b),  when  nearly  hatched,  is  white  in  color,  but  later 
assumes  a grayish  to  yellowish  tinge. 

Mandibles  (Plate  5,  Fig.  78)  black,  slightly  serrated  and  with  two  tufts  of 
curved  hairs  at  the  base. 

First  thoracic  segment  anteriorly  brown.  Laterally  placed  on  the  second  and 
third  thoracic  segments  are  brown  comb-like  marks  with  the  four  teeth  pointing 
backwards. 

On  the  anterior  portion  of  each  abdominal  segment — with  the  exception  of  the 
eighth — are  two  brown  annuli,  or  rings,  encircling  the  body.  The  former  of  these 
two  rings  is  usually  covered  by  the  posterior  margin  of  the  preceding  segment. 
The  hinder  ring  bears  a double  line  of  fine  black  hairs  and  also  a number  of  small 
fleshy  projections  or  pseudopods.  The  eighth  abdominal  segment  serves  the 
purpose  of  a respiratory  syphon.  Its  posterior  margin  is  brown  and  from  its  ex- 
tremity can  be  extruded  a small  process  terminating  in  stigmata.  A brown 
curved  longitudinal  mark  is  situated  on  either  side  of  the  eighth  segment.  The 
anus  is  placed  at  the  base  of  this  segment.  Length  35  mm. 

The  pupal  case  is  chestnut-brown  in  color,  with  the  thoracic  tubercles  darker. 
Each  of  these  tubercles  bears  a spine.  The  abdominal  segments  are  apically  ringed 
with  backward  projecting  spines.  The  anal  segment  terminates  in  a cluster  of 
six  teeth  (Plate  12,  Fig.  148),  the  dorsal  pair  larger  than  the  lateral  and  ventral 
pairs.  Length  20  mm. 

The  pupal  aster  has  been  figured  by  Neave  (Plate  14,  Fig.  175, 
a-d );  it  is  of  the  regular  type  and  the  dorsolateral  combs  have 


WERNER  MARCHAND 


97 


long  spines,  which  are,  however,  shorter  and  stouter  (especially  in 
the  female)  than  those  of  Tabanus  corax . 

Tabanus  bovinus  Linne. — This  is  one  of  the  commonest  species  of 
the  genus  in  Europe,  the  largest  species  in  Sweden.  It  has  a wide 
distribution  and  occurs  even  in  South  Africa. 

The  larvae  were  found  by  Degeer  (1760)  in  the  soil  of  a meadow. 
Placed  in  earth  which  was  renewed  from  time  to  time  some  of  them 
gave  pupae.  I give  Degeer’ s original  report  in  translation  from  the 
German. 

The  larvae  of  these  flies,  which  have  not  been  recorded  by  any  one  before  me, 
live  in  the  ground,  and  I have  described  them  already  in  the  Swedish  Proceedings.16 
When  in  the  month  of  May,  I turned  over  the  earth  of  a meadow,  I found  many  of 
them,  and  having  placed  seven  or  eight  in  a jar  with  fresh  earth  which  was  renewed 
from  time  to  time,  I was  aware,  on  June  12,  1760,  that  one  of  them  had  turned 
to  a pupa,  and  had  in  part  crawled  out  from  the  earth,  being  still  fixed  in  it  by  the 
abdomen.  I dug  for  the  remaining  larvae,  but  found  only  three  of  them,  which 
pupated  later,  and  in  the  same  way  protruded  with  half  of  their  body  from  the 
earth.  At  last  I found  one  more  small  dead  larva.  I presume  that  those  which 
pupated  have  eaten  up  the  others. 

The  largest  of  these  larvae  (Plate  4,  Fig.  59,  a,  c)  was  about  lh  inches  long, 
and  in  the  middle  lines  in  diameter  (as  seen  in  the  figure),  very  similar 
to  the  larvae  of  the  large  crane-flies.  The  body  was  cylindric,  of  almost  equal 
diameter  all  along  its  course,  narrowed  and  pointed  at  the  head,  twelve-seg- 
mented, the  last  segment  small  and  wart-like. 

Color  whitish  gray  and  yellowish ; a number  of  black  transverse  bands  formed 
by  the  transverse  ridges  and  some  transverse  stripes  in  the  incisions  between  the 
segments.  The  small  head  is  shining  brown.  Under  the  lens  the  skin  appears 
also  shining,  and  covered  with  very  fine  longitudinal  ridges. 

The  head  is  elongate,  horny,  bearing  several  parts  difficult  to  distinguish  as  they 
are  constantly  in  motion,  also  with  two  small  short  antennae,  some  pointed  parts 
placed  below,  and  two  large  horny  black  mandibles  placed  above  the  latter,  as 
long  as  the  head  and  curved  downwards.  If  a larva  was  held  between  the  fingers, 
it  exserted  the  hooks,  attached  itself  to  the  skin  with  them,  and  pulled  the  con- 
tracted body  up.  Probably  it  burrows  its  way  in  the  earth  by  means  of  these 
hooks.  While  resting,  the  head  is  withdrawn  into  the  first  segment,  and  this  in 
turn  into  the  second  segment,  so  that  the  anterior  part  becomes  of  the  same 
diameter  as  the  rest  of  the  body.  The  two  last  segments  can  also  be  retracted 
into  the  third  last  one,  in  a similar  way. 


16  Bromsarne’s  Ursprung. 


98 


THE  EARLY  STAGES  OF  TABANID  iE 


The  last  segment  (Plate  4,  Fig.  59,  c ) has  the  aspect  of  a small  soft  textured 
conical  wart;  at  its  end  there  is  a small,  elongate  protruded  horn-like  brownish 
yellow  piece  placed  vertically,  which  I assume  to  be  a spiracle,  as  a longitudinal 
fissure  is  discernible.  Under  the  segment  before  the  last,  near  the  segment 
preceding  it,  there  is  a fleshy  prominence,  also  with  a longitudinal  fissure  in  the 
middle,  the  anus. 

On  the  body  seven  prominent  blackish  ridges  are  found  situated  anteriorly 
on  the  fourth,  fifth,  and  the  following  segments,  to  the  tenth,  including  the 
latter.  At  the  sides  and  below  fleshy  warts  take  the  place  of  feet.  In  con- 
tracting the  rings  the  interior  parts  are  drawn  in. 

The  nymph  (Plate  4,  Fig.  59,  b,  d),  1 inch  in  length,  of  the  same  thickness  as 
the  larva,  cylindric  excepting  the  last  segment,  which  is  much  smaller.  It  trans- 
formed into  a large  horse-fly  while  I had  expected  that  a large  crane-fly  would 
appear.  The  color  was  brownish  gray;  darker  at  the  abdomen  and  the  other 
parts.  The  abdomen  was  eight-segmented;  at  the  posterior  margin  of  each  seg- 
ment was  a fringe  of  long  gray  hairs.  On  the  last  segment  at  the  tip  there  are  six 
hard  horn-like  points  (Plate  4,  Fig.  59,  d ),  by  means  of  which  the  nymph  works 
its  way  out  of  the  earth.  Head,  thorax,  and  wing  cases,  or  the  whole  thoracic 
region  together  shorter  than  the  rest.  Anteriorly,  on  the  head,  there  are  two 
small  brown  tubercles,  each  of  them  bearing  a hair,  probably  spiracles.  At  the 
side  of  each  tubercle  an  elongate  and  equally  brownish  point,  appressed  flatly 
to  the  head,  directed  backwards  and  jointed  in  the  middle,  probably  the  anten- 
nal sheaths.  If  the  nymph  is  touched,  it  carries  out  worm-like  movements  with 
the  abdomen. 

Early  in  July  the  fly  hatched  out.  The  pupal  skin  splits  open  dorsally  along- 
side the  thoracic  shield,  and  at  the  sides  of  the  head.  Internally,  there  are  in 
the  cuticle  of  the  head  two  long  horn-like  spines,  the  function  of  which  is  unknown 
to  me. 

These  observations  of  Degeer  are  remarkable  for  their  precision.  A 
number  of  details  which  have  been  incorrectly  represented  in  tabanid 
larvae  by  several  later  authors,  as  the  number  of  segments,  position 
of  the  anus,  etc.,  have  been  correctly  described.  Nothing  essential 
is  omitted.  Degeer,  in  1760,  calls  attention,  like  del  Guercio  in 
1913,  to  the  similarity  between  certain  tabanid  larvae  and  those  of 
crane-flies,  but  while  the  latter  is  satisfied  to  state  that  there  is  no 
appreciable  difference  between  them,  Degeer’ s description  of  the 
Tabanus  larva  remains  fully  characteristic  of  the  group  and  prob- 
ably also  of  the  species,  though  before  the  larvae  hatched,  he  had  ex- 
pected them  to  become  tipulids. 


WERNER  MARCHAND 


99 


Westwood  (1840)  has  briefly  translated  Degeer’ s description,  and 
I give  his  summary  to  complement  the  above  rather  imperfect  trans- 
lation : 

“The  larva  of  Tabanus  bovinus  Degeer  (L)  is  found  in  the  earth,  and  is  of  an 
elongated  subcylindric  form,  attentuated  at  each  end,  especially  in  front;  it  is 
destitute  of  feet,  twelve-jointed,  having  the  head  distinct,  narrow,  elongate, 
horny,  armed  with  two  strong  curved  hooks,  antennae,  and  palpi;  the  fourth  to  the 
tenth  segments  having  an  elevated  dorsal  papillose  ridge  used  in  progression; 
the  terminal  segment  is  minute  and  tuberculiform ; the  pupa  is  naked,  incomplete, 
elongated,  subcylindric,  with  six  spines  at  the  end  of  the  body;  the  margins  of 
the  abdominal  segments  ciliated,  and  the  forehead  bi-tubercled.” 

Westwood  also  reproduced  Degeer’s  figures,  though  very  imper- 
fectly; also  Macquart,  1834. 

No  further  observations  have  been  published  on  the  early  stages  of 
this  species,  since  Degeer. 

Tabanus  bromius  Linne. — The  larvae  of  Tabanus  bromius  live,  ac- 
cording to  Beling,  by  preference  in  the  grass-covered  soil  of  meadows, 
fields,  and  similar  places.  They  are  often  brought  to  the  surface  by 
moles,  and  in  the  spring  and  summer,  1874,  Beling  found  them,  as 
also  later  on  the  pupae,  especially  frequently  on  meadows  in  fresh 
mole  hills.  The  pupal  stage  lasts  usually  between  two  and  three 
weeks,  and  the  imagos  begin  to  appear  in  the  second  half  of  the 
month  of  June.  The  larvae  feed  by  sucking  the  contents  of  earth- 
worms, larvae  and  pupae  of  other  insects,  and,  if  there  is  lack  of  other 
food,  of  their  own  kind,  but  they  seem  to  be  able  to  subsist  in  case 
of  necessity  on  earth  alone,  in  which,  as  Beling  says,  he  kept  them 
for  months  until  pupation. 

I assume  that  the  larvae,  if  they  subsist  on  earth,  will  in  fact  sub- 
sist on  its  organic  contents  in  a similar  way,  as  is  the  case  with  earth- 
worms. Moreover,  small  earthworms  and  insect  larvae  are  easily 
overlooked  by  the  observer  if  the  earth  used  is  not  specially  sterilized. 

Larva. — Length  up  to  16  mm.,  width  4 mm.,  color  pale  yellow,  strong,  silky, 
shining,  with  distinct  dense  and  fine  longitudinal  striation,  with  twelve  body 
segments,  excepting  the  small  narrow  brown  head,  which  can  be  retracted  into  the 
first  segment.  The  latter  in  the  middle  of  dorsal  surface  with  a wall-like  longi- 
tudinal prominence,  which  is  covered  in  its  anterior  part  with  short  hairs,  and  on 


100 


THE  EARLY  STAGES  OF  TABANID^ 


each  side  is  provided  with  a rounded  densely  brush-like  denticulate  tubercle. 
Antennae  not  discernible,  palpi  very  short,  one-jointed,  thick.  First  body  seg- 
ment short,  obtusely  cone-shaped,  retractile,  and  merging  into  the  second  seg- 
ment without  distinct  border.  Last  segment  short  and  much  narrower  than  all 
the  preceding,  cupola-shaped,  bearing  on  the  anterior  part  of  the  under  side  the 
more  or  less  prominent  half  circular  anus  crossed  by  a deep  longitudinal  furrow  or 
fissure.  The  tip  of  the  last  segment  a roundish,  wart-shaped,  retractile  promi- 
nence, bearing  the  vertical  stigmatal  fissure.  Segments  five  to  ten  inclusive  with 
marginal  swellings  anteriorly.  In  this  ridge  or  ring  eight  protuberances  are  dis- 
tinctly observable,  of  which  two  smaller  ones  are  located  on  the  dorsal  side, 
one  on  each  side,  and  two  pairs,  placed  near  to  one  another,  forming  the  loco- 
motory  swellings  of  the  under  side.  The  surface  of  the  retracted  head  capsule 
visible  through  the  cuticle  of  the  first  segments  appears  as  an  extensive  brownish 
yellowish  area  limited  by  two  broad  blackish  stripes  which,  diverging  from  the 
middle,  are  pointed  and  drawn  out  behind. 

The  pupa  is  likewise  described  by  Beling,  a translation  of  which 
follows. 

Pupa. — Pupa  16  to  18  mm.  in  length,  3.6  to  4 mm.  in  width,  obtuse  at  the 
anterior  end,  slightly  narrowed  behind,  of  dirty  greenish  yellow  color,  smooth, 
somewhat  shining,  and  if  older,  with  blackish  borders  of  the  segments.  Above 
the  front  five  to  six  small  flat  brownish  tubercles  or  warts,  of  which  the  two 
lowest  are  enlarged  and  tooth-like,  the  two  upper  ones  flatly  truncated,  bear- 
ing a short  blackish  brown  hair  in  the  middle  of  the  truncation.  On  each 
side  of  these  frontal  tubercles  is  a short  tooth-like  outwardly  directed  spine. 
Above  the  frontal  tubercles  are  two  small  wart-like  tubercles  each  bearing  a 
short  black  bristle.  Lower  ventral  side  of  thorax  on  each  side  with  two 
small  brown  warts  bearing  a backwardly  directed  closely  appressed  hair, 
and  with  an  elongate  black  spot,  these  together  forming  two  rows  diverging 
posteriorly.  Abdomen  nine-segmented,  first  segment  Very  short,  third  to  eighth 
segments  inclusive  on  each  side  with  two  parallel  longitudinal  depressions  rather 
distant  from  one  another,  together  forming  two  depressed  lines  running  laterally 
alongside  the  abdomen.  In  the  middle  of  these  depressions  on  each  of  the  six  seg- 
ments mentioned  and  in  its  anterior  part  a short  spine-shaped  prominence  and  a 
similar  prominence  also  on  the  second  segment  immediately  behind  the  wing 
cases.  Third  to  eighth  abdominal  segments  near  its  posterior  margin  with  a 
circle  of  densely  placed  yellowish  to  brownish  or  even  blackish  hairs  of  uneven 
length  and  more  or  less  completely  appressed  backwards  to  the  surface.  Last 
abdominal  segment  with  six  short  thick  outwardly  diverging  spines  with  dark 
brown  tips,  of  which  four  are  placed  in  a horizontal  row;  namely,  a strong  one 
on  each  side  and  two  weaker  ones  in  the  middle.  Wing  and  leg  cases  not  very 
strongly  marked,  of  the  same  color  as  the  rest  of  the  body,  reaching  to  the  anterior 
border  of  the  third  abdominal  segment. 


WERNER  MARCHAND 


101 


The  pupa  of  Tabanus  bromius  L.  has  been  figured  also  by  Surcouf 
and  Ricardo  (1909);  the  previous  observations  by  Beling  have  not 
been  observed  by  these  authors. 

This  pupa  (Plate  12,  Fig.  151)  was  collected  in  the  earth  of  a rail- 
road embankment  at  Longny,  Orne,  France,  by  M.  E.  Cordier,  from 
whom  the  authors  received  it.  The  adult  died  in  the  act  of  hatching; 
it  proved  to  be  a male  of  Tabanus  bromius  L.;  having  left  the  pupal 
shell  half  way,  it  had  been  unable  to  free  itself  in  spite  of  numerous 
efforts  as  proved  by  the  pupal  shell  being  unusually  drawn  out  in 
length.  The  manner  of  the  hatching  of  the  adult  is  evident  from 
the  examination  of  this  rare  piece;  the  head  causes  the  top  of  the 
shell  to  burst  and,  consequently,  to  break  open  longitudinally,  under 
the  pressure  of  the  insect,  down  to  the  base  of  the  first  abdominal 
segment,  which  remains  intact  like  the  following  segments.  When 
the  adult  has  reached  this  stage  of  its  development,  it  takes  flight, 
and  goes  in  search  of  food  as  sopn  as  it  is  dry. 

Tabanus  carolinensis  Macquart. — Of  this  North  American  species, 
Malloch  has  given  us,  in  his  synoptic  table,  the  following  data  on  the 
pupal  stage: 

“Pupa. — Dorsal  abdominal  segments,  except  first,  armed  with  an  irregular 
transverse  series,  or  two  such  series,  of  very  stout  thorns,  their  bases  very  much 
dilated,  slightly  caudad  of  which  series  there  are  sometimes  a few  widely  separated, 
much  longer  spines.  Seventh  dorsal  abdominal  segment  with  10  or  12  moderately 
long  thorns  in  a continuous  transverse  series,  slightly  cephalad  of  which  is  a 
transverse  series  of  very  stout  thorns  longitudinally  in  line  with  the  spaces  be- 
tween the  thorns  of  the  posterior  series.” 

No  illustrations  are  given. 

Tabanus  corax  Loew. — A large  species  with  wings  uniformly  dusky 
to  the  edge  of  the  apex.  Habitat,  Africa.  According  to  Neave, 
common  on  the  southern  side  of  Mt.  Mlanje,  southern  Nyasaland,  in 
the  more  wooded  areas  within  the  belt  of  heavy  rainfall.  On  the 
wing  from  the  end  of  November  to  the  beginning  of  January. 

We  are  indebted  to  Neave  (1915)  for  a knowledge  of  its  life  history. 

The  flies  were  kept  by  Neave  in  a comparatively  large  cage  made  of 
mosquito  netting  and  wood,  each  partition  measuring  about  5 by  4 
by  3 feet,  in  which  were  boxes  containing  grasses  and  growing  plants. 


102 


THE  EARLY  STAGES  OF  TABANIDiE 


The  mosquito  netting  was  loosely  attached  to  the  cage,  so  that  the 
shock  to  a fly  in  striking  against  it  was  minimized. 

One  or  two  captured  females  of  Tabanus  corax  oviposited  in  these 
cages,  the  process  in  one  instance  taking  nearly  an  hour,  between 
3 and  4 p.m.  Many  egg  masses  of  this  species  were  also  obtained  in 
the  bush,  always  on  reeds  or  grasses  overhanging  mud.  While  the 
female  is  ovipositing  she  is  not  easily  disturbed,  as  in  the  case  of  Ta- 
banus biguttatus  (King),  and  on  one  occasion  one  of  Neave’s  collec- 
tors brought  him  the  reed,  fly  and  all,  from  more  than  a mile  distant 
without  disturbing  the  female.  The  egg  mass  with  its  cement  cov- 
ering is  pure  white  when  first  laid,  becoming  dark  gray  as  it  hardens. 
The  cement  which  covers  these  egg  masses  must  be,  according  to 
Neave,  water-proof  and  insoluble,  as  some  individuals  from  them 
succeeded  in  hatching  even  though  the  egg  mass  had  been  kept  in 
70  per  cent  alcohol  for  two  days. 

The  egg  masses  of  Tabanus  corax  are  of  the  usual  tabanid  type,  all 
the  individual  spindle-shaped  eggs  being  laid  with  their  long  axes 
in  the  same  direction.  In  the  cases  observed  hatching  took  place 
about  the  fifth  day,  but  this  would  be  likely  to  be  lengthened  or 
shortened  in  some  cases,  according  to  the  temperature.  The  process 
of  hatching  takes  place  very  suddenly.  The  egg  mass  splits  in  the 
midline,  following  the  long  axis,  and  the  small  larvae  emerge  almost 
simultaneously,  forming  a large  quasi- viscous  drop  which  falls  bodily 
from  the  reeds,  etc.,  into  the  water  or  mud  below. 

A number  of  newly  hatched  larvae  were  obtained  from  collected 
egg  masses,  generally  found  on  reeds  overhanging  swampy  ground. 
The  young  larvae  grow  very  slowly  at  first.  Neave  figures  the 
syphon  and  anal  segment  of  one  of  these  young  larvae.  The  figure 
(Plate  10,  Fig.  120)  shows  the  peculiar  Graber’s  organ,  somewhat 
tongue-shaped  or  triangular,  and,  according  to  Neave,  attached  by 
fine  strands  of  muscle  from  each  of  the  three  corners,  apparently  to 
the  body  wall.  It  lies  above  the  gut  immediately  below  the  dorsal 
integument  and  seems  to  be  capable  of  motion  independent  of  the 
general  body  movements.  The  organ  contains  a number  of  pairs  of 
small  black  pyriform  bodies. 

Neave  obtained  the  larvae  of  Tabanus  corax  in  considerable  num- 
bers. Adult  specimens  are  large,  from  40  to  45  mm.  in  length,  and 


WERNER  MARCHAND 


103 


distinct,  having  a thick  rough  integument  of  a dull  reddish  color, 
with  a tendency  to  two  more  definite  patches  of  darker  red  on  the 
dorsal  portions  of  the  last  two  segments.  The  general  coloration 
appears  to  be  largely  due  to  the  presence  of  foreign  bodies  in  the 
rough  skin.  The  syphon  is  very  short,  as  seen  in  the  figure  (Plate 

5,  Fig.  67). 

These  larvae  were  most  ferocious  cannibals  in  all  stages  and  very 
troublesome  in  the  laboratory,  as  they  seemed  to  have  unlimited 
power  of  wandering  about,  even  over  dry  surfaces.  They  fre- 
quently succeeded  in  reaching  the  receptacles  in  which  other  species 
were  kept,  and  in  destroying  the  larvae  in  them. 

In  the  pupal  aster  (Plate  15,  Fig.  181,  a,  b,  c ) the  dorsal  hooks  of  the 
male  are  somewhat  larger  than  those  of  the  female.  The  dorso- 
lateral comb  is  large  and  composed  of  very  long  and  fine  spines.  The 
pupal  asters  of  male  and  female,  and  the  dorsolateral  comb  of  the 
female  are  figured. 

Tabanus  cordiger  Meigen. — A species  described  by  Meigen  (1820), 
and  widely  spread  in  Europe,  chiefly  in  the  South. 

Brauer  (1883)  is  the  first  to  figure  the  larva  of  this  species  (Plate 

6,  Fig.  88,  a-d),  but  gives  no  description. 

Picard  and  le  Blanc  report  that  they  found,  on  March  4, 1913,  in  the 
trunk  of  a poplar  at  the  edge  of  the  Mousson  River,  near  Montpellier, 
France,  an  elongate,  whitish  larva,  pointed  at  both  ends  and  having 
a ridge,  or  prominent  ring,  on  each  segment,  a larva  which  appeared 
to  them  to  be  that  of  a tabanid.  The  larva  was  placed  in  a jar  con- 
taining pieces  of  decaying  wood  from  the  poplar  tree  in  which  it 
had  been  found,  and  was  left  without  any  other  food. 

The  exact  time  of  pupation  was  not  observed,  but  in  the  meantime 
it  seemed  justifiable  to  assume  that  the  larva  was  satisfied  with  the 
vegetable  food  which  it  obtained  from  the  decaying  wood,  since  one 
month  after  its  capture  it  had  not  yet  transformed.  On  June  10,  a 
male  Tabanus  was  observed  in  the  room,  which  had  just  hatched,  and 
was  determined  by  Dr.  Villeneuve  as  Tabanus  cordiger  Meig. 

The  larva  lived,  at  the  time  of  its  capture,  in  the  stump  of  a poplar. 
The  wood  of  the  stump  was  not  yet  completely  decayed,  but  rather 
soft  and  very  moist.  A careful  search  did  not  reveal  any  other 


104 


THE  EARLY  STAGES  OF  TABANIDHS 


larvae  of  tabanids  or  other  insects,  while  the  felled  trunk  enclosed 
numerous  larvae  of  Tipulidae,  Asilidae  (Eryx),  and  some  larvae  of 
beetles  (Lamellicornia) . 

Picard  and  le  Blanc’s  observations  are  insufficient  for  an  exact  mor- 
phological description  of  the  larva,  but  a brief  description  of  the 
pupa  is  given,  based  on  the  pupal  shell  left  after  the  hatching.  A 
translation  of  this  description  follows: 

Pupa. — (Plate  12,  Fig.  136.)  Slightly  curved  inwards  ventrally  in  its  posterior 
part;  measures  20  mm.  in  length,  4 mm.  in  width,  and  3 mm.  in  height.  The 
anterior  part  (Plate  13,  Fig.  155),  extending  to  the  scutellar  segment,  and  com- 
prising the  head,  thorax,  legs,  and  wings,  is  smooth  and  unarmed,  except  for  some 
dorsal  hairs.  The  posterior  part  of  the  pupa  (Plate  13,  Fig.  158)  is  composed  of 
seven  segments,  surrounded  at  about  the  second  third  from  their  base  with  a 
crown  of  stiff  and  unequal  bristles.  The  tubercles  described  by  Surcouf  in  an 
unidentified  pupa  were  not  observed.  The  last  segment  is  terminated  by  two 
three-toothed  tubercles,  at  the  base  of  which  is  found  ventrally  a cup-shaped 
formation  which  possibly  corresponds  to  the  anus  of  the  larva.  The  preabdom- 
inal segment  and  the  first  six  abdominal  segments  bear  on  each  side  a spiracle 
placed  towards  the  base  of  the  segment,  at  the  height  of  the  anterior  third.  The 
crown  of  bristles  of  the  seventh  segment  is  incomplete  and  interrupted  dorsally. 

The  emergence  of  the  adult  causes  at  the  anterior  part  of  the  pupal  shell  a fis- 
sure which  separates  it  into  three  wings,  two  dorsolateral  ones  and  a ventral 
one  of  irregular  shape.  The  latter,  in  the  shape  of  an  elongate  hexagon  of  4 mm. 
length  by  3 mm.  width,  shows  a characteristic  ornamentation  which  can  be 
traced  on  the  figure  given. 

At  the  anterior  part  two  tubercles  are  found,  each  bearing  a bristle;  somewhat 
below  two  slight  ridges  which  meet  in  the  median  line,  further  down  two  doubled 
tubercles,  placed  between  two  triangular  thickenings,  finally,  more  posteriorly,  two 
pairs  of  small  tubercles  between  which  two  depressions  with  inner  convexities 
are  found.  A little  in  front  of  the  point  of  attachment  of  the  piece,  two  lateral 
triangular  expansions  are  observed.  It  is  probable  that  the  first  two  tubercles 
correspond  to  the  antennae  of  the  larva  and  the  others  to  the  mouth-parts. 

These  observations  show,  according  to  Picard,  that  certain  species 
of  tabanids  may  have  wood-inhabiting  larvae,  and  that  their  habits 
are  more  variable  than  one  would  suppose.  Picard’s  paper  is  accom- 
panied by  three  figures. 

The  observations  made  by  Paoli  on  Graber’s  organ  (page  37)  have 
possibly  been  made  on  this  species. 


WERNER  MARCHAND 


105 


Tabanus  costalis  Wiedemann. — Habitat,  eastern  North  America. 
The  species  is  very  common,  and  a pest  to  stock.  Of  its  early  stages 
we  know  little.  There  are  no  data  available  on  its  oviposition,  and 
although  Hine  (1903),  while  speaking  of  the  control  of  tabanids  in 
Louisiana,  mentions  that  oviposition  in  tabanids  often  takes  place 
not  over  water  but  over  damp  ground,  and  that  “one  finds  the  eggs 
of  costalis  and  a number  of  other  species  in  such  places  quite  fre- 
quently,” he  gives  no  description  of  the  eggs. 

The  larva  seems,  according  to  Hart,  to  be  normally  a terrestrial 
larva.  He  has  found  it  two  or  three  times  in  the  earth  of  corn  fields 
in  Champaign  County,  Illinois.  The  dates  given  are  May  31  and 
June  4.  Specimens  were  placed  in  a breeding  cage,  and  an  imago  of 
costalis  was  secured  from  them.17  Hart  believes  that  the  species  is 
single-brooded.  His  description  of  larva  and  pupa  follows: 

“Larva. — Length  20  mm.,  diameter  2.7  mm.  Prothorax  with  lateral  shining 
areas  about  as  long  as  the  dorsal,  coarsely  striate,  a smooth  spot  near  center  of 
disk;  dorsal  and  ventral  areas  of  thorax  smooth,  a few  strise  on  those  of  meta- 
thorax, especially  posteriorly;  remaining  areas  moderately  striate,  lateral  areas 
of  abdomen  a little  more  finely  striate  than  the  others;  all  more  or  less  shining.” 

“Dark  annuli  pale,  narrow,  longitudinal  stripes  scarcely  present;  false  feet 
with  dull  pubescent  crests,  their  sides  rather  finely  striate;  a narrow  dark  annu- 
lus at  base  of  respiratory  tube,  another  around  base  of  last  segment,  enclosing 
anal  prominence  and  giving  off  a pair  of  lateral  stripes,  the  lower  one  longer;  no 
projecting  spine  seen.” 

“ Pupa  (from  defective  cast  skin  of  male). — Length  20  mm.,  diameter  3 
mm.  Light  fuscous  brown,  shining ; abdomen  smoothly  wrinkled,  slightly  opaque ; 
prothoracic  spiracular  tubercles  slightly  but  nearly  equally  elevated,  free  margin 
rounded  at  tip,  rima  not  vertical,  evenly  arcuate,  slightly  hooked  in  front.” 

“Abdominal  spiracular  tubercles  small,  subtriangular,  narrower  behind,  ob- 
liquely subconical,  much  shorter  than  basal  diameter,  bearing  a very  small  sub- 
circular  rima;  fringes  formed  of  unequal  pale  spines,  the  longer  ones  sparse  on 
seventh  segment  above;  outer  terminal  teeth  twice  as  large  as  lower  pair,  directed 
laterally  and  slightly  backwards;  upper  pair  smallest,  directed  upwards;  ventral 
fringe  of  last  segment  not  noticeably  webbed;  lateral  tufts  rather  high,  not  near 
ends  of  ventral  fringe.” 

Hart’s  material  was,  as  he  says,  “not  in  the  best  condition  for 
accurate  comparisons.” 

17 1 have  since  found  the  larva  of  this  species  in  the  muddy  banks  of  Lake 
Carnegie  in  Princeton,  N.  J.,  which  shows  that  it  is  not  always  terrestrial. 


106 


THE  EARLY  STAGES  OF  TABANIDiE 


Tabanus  desertus  Walker. — South  America,  British  Guiana.  The 
larval  and  pupal  stages  have  been  observed  by  Bodkin  and  Cleare  in 
the  coast  region  of  British  Guiana.  Numbers  of  larvae  were  found  in 
a damp  accumulation  of  sweepings  situated  at  the  end  of  a drain 
leading  from  a large  cattle  pen.  Several  of  these  larvae  were  secured 
and  kept  in  the  laboratory  under  frequent  observation.  Although 
supplied  with  a quantity  of  suitable  food  the  largest  larva  eventually 
consumed  its  companions  and  pupated.  After  sixteen  days  a female 
Tabanus  desertus  emerged.  The  pupal  aster  (terminal  end  of  the 
pupa,  showing  the  arrangement  of  the  spines)  is  figured  (Plate  15, 
Fig.  180,  a,  b). 

T abanus  ditceniatus  Macquart. — The  distribution  of  this  tabanid  as 
given  by  Austen  is  wide.  In  Africa  it  occurs  from  the  Transvaal  in 
the  South  to  Egypt  in  the  North,  while  outside  the  bounds  of  Africa 
it  is  found  in  Baluchistan,  India,  Ceylon,  China,  and  Japan.  In  the 
Anglo-Egyptian  Sudan  it  occurs  fairly  commonly  in  the  South,  but 
until  1910  it  had  not  been  recorded  from  the  northern  provinces,  when 
King  began  his  studies  on  this  species. 

The  larvae  were  taken  early  in  March,  1910,  in  a small  water  chan- 
nel, locally  known  as  a “Gadwal,”  on  the  estate  belonging  to  the 
Sudan  Plantation  Syndicate  Ltd.,  at  Zeidab,  Berber  Province.  The 
water  was  for  the  most  part  overgrown  with  a covering  of  green 
slime,  and  when  this  was  cleared  away  a few  larvae  could  generally 
be  seen  on  the  surface.  On  stirring  up  the  mud  at  the  bottom  and 
edges  of  the  water  more  appear,  while  if  one  waited  for  an  hour  or  so, 
specimens  would  continue  to  rise.  They  were  apparently  living  in 
the  mud  at  the  bottom  of  the  pools  and  coming  periodically  to  the 
surface  to  breathe.  They  could  be  seen  rising  to  the  surface  by  a 
lashing  motion,  and  if  left  undisturbed  would  after  a few  seconds 
sink  out  of  sight  again. 

Some  forty  odd  larvae  of  various  sizes  were  taken  on  March  9 and 
placed  in  a jar  containing  water,  slime,  and  hollow  grass  stems;  most 
of  these  had  disappeared  by  the  next  morning,  the  larger  ones  having 
devoured  the  smaller  ones.  On  March  10  more  than  a hundred  were 
obtained,  and,  together  with  the  survivors  from  the  previous  day, 
were  divided  among  three  jars  (only  three  being  available),  two  con- 


WERNER  MARCHAND 


107 


taining  wet  mud,  and  the  third  water  with  hollow  grass  stems  and 
other  debris.  Earthworms  were  provided  as  food,  but  were  not 
taken  very  readily;  the  larvag  seemed  to  prefer  to  eat  each  other. 
They  were  brought  to  Khartoum  on  March  1 1 , and  the  following 
morning  each  of  the  thirty-three  which  were  still  living  was  placed 
in  a separate  jar  containing  clean  river  sand  and  water.  They  fed 
freely  on  tiny  earthworms,  but  their  numbers  steadily  decreased 
until  about  April  16,  when  thirteen  survivors,  having  attained 
maturity,  ceased  to  feed.  Up  to  this  stage,  if  the  sand  in  which  they 
were  living  was  allowed  partially  to  dry  out,  they  became  very  rest- 
less until  water  was  given  them  again,  but  hereafter  they  preferred 
sand  which  was  only  slightly  damp.  In  appearance  as  well  as  habit 
they  altered  considerably  at  this  stage  of  their  existence.  While 
young  and  growing,  they  possessed  well  developed  prolegs  and  con- 
spicuous dark  dorsal  markings;  now,  however,  their  prolegs  became 
small,  and  in  color  they  appeared  uniform  yellowish  white. 

These  thirteen  larvae  were  left  undisturbed  until  May  26,  when  one 
specimen  was  washed  and  was  found  to  have  pupated,  probably 
within  the  previous  two  days,  as  the  eyes  had  not  begun  to  show  the 
color  which  they  acquired  later.  On  the  following  day,  two  more 
pupae  were  discovered  in  the  sand.  Prior  to  pupating  the  larvae 
had  made  a number  of  tunnels  in  the  sand,  and  the  pupae  were  lying 
in  a more  or  less  upright  position  in  the  tunnels  and  near  the  surface. 

On  April  28  King  left  Khartoum,  and  traveled  in  the  provinces 
until  May  30,  by  which  date  one  larva  had  died  and  twelve  com- 
pleted their  life  cycles,  producing  eight  females  and  four  males. 
The  first  had  emerged  on  April  29  or  30,  so  the  period  passed  in  the 
pupal  stage  was  probably  about  six  days. 

King’s  detailed  description  is  given  in  about  the  following  words. 

Immature  Larva. — (Plate  3,  Fig.  47;  Plate  4,  Fig.  57,  a-d.)  Length  18 
mm.  Color  yellowish  white,  with  dark  markings  composed  of  pubescence. 
Mandibles  dark  brown  to  black,  slightly  serrated.  Anterior  margins  of  the 
meso-  and  metathoracic  segments  dark,  except  on  the  venter.  A ring  of  pseudo- 
pods, eight  in  each  ring,  two  dorsal,  two  lateral,  four  ventral,  on  the  anterior  third 
of  each  abdominal  segment  except  the  eighth,  well  developed,  except  the  dorsal 
pairs  on  the  first  and  second  segments,  and  bearing  spines  or  hooks.  Spines  are 
also  present  between  the  pseudopods  on  each  ring.  The  rings  on  the  first  and 


108 


THE  EARLY  STAGES  OF  TABANID^ 


second  segments  edged  before  and  behind  with  dark  pubescence,  especially  on 
the  dorsum,  the  pubescence  extending  between  the  dorsal  and  lateral  pseudo- 
pods, thus  enclosing  the  dorsal  pseudopods  in  a dark  ring.  On  each  of  the  third 
to  the  seventh  segments  inclusive  is  a patch  of  dark  pubescence  between  the 
lateral  and  the  dorsal,  and  between  the  dorsal  pseudopods,  three  patches  on 
each  ring,  the  median  patch  being  conspicuous.  To  the  naked  eye  these  me- 
dian patches  constitute  a median  dorsal  line  of  black  dots. 

On  each  of  the  third  to  the  sixth  segments,  inclusive,  are  two  patches  of  dark 
pubescence,  immediately  anterior  to  the  dorsal  pseudopods.  The  posterior  mar- 
gin of  the  eighth  segment  bears  dark  pubescence.  The  surface  of  the  larva 
other  than  that  bearing  pubescence  is  shiny  and  longitudinally  striated. 

Mature  Larva. — (Plate  4,  Fig.  57,  b;  Fig.  64,  a,  b,  c .)  Length  25  mm.  Color 
yellowish  white.  Mandibles  dark  brown  to  black,  slightly  serrated.  Thoracic 
segments  shining  and  longitudinally  striated,  except  the  anterior  margins,  which 
are  opaque  and  pubescent.  On  the  prothoracic  segment  are  five  longitudinal 
grooves,  one  ventral,  two  sublateral,  two  subdorsal,  not  extending  to  the  posterior 
border.  On  the  meso-  and  metathoracic  segments  are  eight  such  grooves,  four 
on  either  side.  The  first  abdominal  segment  bears  one  pair  of  ventral  pseudo- 
pods;18 the  second  segment  one  pair  of  ventral  and  one  pair  of  lateral;  the  third 
to  the  seventh,  two  pairs  of  ventral  and  one  pair  of  lateral.  Traces  of  most  of 
the  other  pseudopods  are  present,  especially  of  the  dorsal  pseudopods  on  the 
fourth  to  the  seventh  segments.  The  pseudopods  bear  small  colorless  spines  or 
hooks,  and  similar  though  smaller  spines  are  situated  between  the  pseudopods 
and  on  the  dorsum  of  the  first,  second,  and  third  segments  where  the  pseudopods 
are  wanting.  On  the  dorsum  of  the  first  and  second  segments  these  spines  con- 
stitute a double  band.  The  posterior  third  of  each  abdominal  segment  is  shiny 
and  longitudinally  striated.  The  anus  is  edged  with  pubescence.  The  syphon 
when  exserted  appears  rather  shorter  than  the  eighth  segment. 

Pupal  Case. — (Plate  11,  Fig.  129;  Plate  12,  Fig.  141.)  Length  17  mm. 
Color  yellowish  brown,  thoracic  tubercles  and  abdominal  spiracles  darker,  the 
former  bearing  hairs.  On  the  posterior  third  of  the  second  to  the  seventh  ab- 
dominal segments  is  a ring  of  backwardly  pointed  spines,  shortest  on  the  second 
segment  and  longest  on  the  seventh.  The  eighth  segment  (Plate  12,  Fig.  141, 
a,  b)  terminates  in  a coronet  of  six  teeth,  chestnut  brown  in  color,  darker  at  the 
tips,  the  lateral  pair  by  far  the  largest,  the  dorsal  and  ventral  pairs  being  about 
equal  in  size,  the  former  sometimes  slightly  the  larger.  The  dorsal  pair  arises 
from  between  the  lateral  teeth,  the  four  teeth  constituting  a row.  Ventrally 
placed  to  this  coronet  are  two  rows  of  similar  teeth,  each  row  consisting  of  from 
two  to  five  teeth,  the  two  rows  together  constituting  an  interrupted  trans- 
verse row.  These  teeth  are  unequal,  and  vary  in  size  and  number  in  different 
specimens. 

18  King  uses  the  term  “pseudopod”  instead  of  “proleg”  which  should  be  used, 
pseudopod  being  used  in  protozoology. 


WERNER  MARCHAND 


109 


The  pupa,  when  first  formed,  is  yellow  with  a greenish  tinge,  especially  on  the 
thorax.  Later,  as  the  imago  develops,  the  eyes  show  as  deep  maroon  and  the 
thorax  becomes  generally  darker. 

On  Tabanus  ditceniatus  we  possess  also  some  notes  by  Patton  and 
Cragg,  who  observed  the  species  in  Madras  (1913). 

Tabanus  ditceniatus,  being  a small  species,  oviposits,  according  to 
these  authors,  “on  blades  of  grass  just  at  the  edge  of  a shallow  stream, 
or  on  the  leaves  of  the  lotus  plant  at  the  edges  of  small  ponds,  but 
never  over  deep  water.”  It  should  then  fall  under  the  heading  of 
those  tabanids  in  which  the  larvae  are  said  to  have  no  air  sacs  and  to 
die  when  falling  into  deep  water. 

The  eggs  of  Tabanus  ditceniatus  measure,  according  to  Patton  and 
Cragg,  about  1.2  mm.  in  length,  and  2 mm.  in  breadth,  being  slightly 
more  slender  than  those  of  Tabanus  bicallosus  Ric.,  an  Indian 
species,  studied  by  Patton  and  Cragg  (1913). 

The  egg  is  figured  by  Patton  and  Cragg  (Plate  1,  Fig.  17),  evidently 
showing  a dark  band  placed  subapically,  the  extreme  tip  being  also 
dark  on  the  figure.  The  egg  mass  of  the  same  species  is  figured  as 
spread  out  in  a single  layer  on  a blade  of  grass  (Plate  2,  Fig.  21). 

The  mature  larva  is  also  figured  (Plate  4,  Fig.  61);  attention  is 
called  to  the  short  stout  syphon  tube. 

The  pupa  is  figured  by  the  same  authors  (Plate  11,  Fig.  133),  and 
the  eighth  abdominal  segment  of  the  pupa  is  figured  (Plate  12,  Fig. 
147)  to  show  the  arrangement  of  the  terminal  teeth  and  the  anus. 

With  these  observations  our  knowledge  of  the  species  is  quite 
complete. 

Tabanus  epistates  Osten  Sacken. — Of  this  North  American  species, 
Malloch  (1917)  has  given  us,  in  his  synoptic  table,  the  following  data 
on  the  pupal  stage: 

“Pupa. — Dorsal  abdominal  segments,  except  first,  armed  with  an  irregular 
transverse  series,  or  two  such  series,  of  very  stout  thorns,  their  bases  very  much 
dilated,  slightly  caudad  of  which  series  there  are  sometimes  a few  widely  sepa- 
rated much  longer  spines.  Seventh  dorsal  abdominal  segment  with  the  poste- 
rior transverse  series  consisting  of  two  long,  widely  separated  spines  on  the 
middle  portion,  and  several,  closely  placed,  on  each  lateral  extremity  which  are 
but  little  caudad  of  the  much  shorter  thorns  of  the  anterior  series.  The  portion 


110 


THE  EARLY  STAGES  OF  TABANID^E 


of  head-capsule  between  bases  of  antennae  slightly  elevated,  rounded,  fairly 
rugose,  and  not  carinate  or  divided  below;  abdominal  armature  moderately  strong, 
distinctly  biserial  laterally.” 

No  illustrations  are  given. 

Tabanus  fraternus  Macquart. — An  African  species,  but  uncommon 
in  so  damp  and  well  wooded  a locality  as  Mt.  Mlanje,  where  a single 
female  was  bred  by  Neave  on  December  16,  1914,  from  a locally 
collected  larva,  which  was  not  recognized  as  distinct  from  that  of 
Tabanus  tamiola. 

The  pupal  aster  (Plate  15,  Fig.  182,  a,  b)  resembles  that  of  Tabanus 
maculatissimus  in  having  a small  papilla  on  each  side  of  the  midline. 
The  dorsolateral  comb  consists  of  only  a small  number  of  spines, 
which  though  rather  long  are  fairly  stout.  The  pupal  aster  and 
dorsolateral  comb  of  the  female  are  illustrated. 

Tabanus  fronto  Osten  Sacken. — This  American  species  has  been 
recorded  from  North  and  South  Carolina,  Texas,  and  Florida.  We 
know  nothing  of  its  egg-laying  habits,  but  the  species  has  been  bred 
repeatedly  from  larvae,  by  Brimley,  in  Raleigh,  North  Carolina.  The 
larvae  of  this  species  occurred  freely  in  the  soil  in  Brimley’s  garden, 
in  a comparatively  dry  locality  situated  on  the  crest  between  two 
water  sheds,  the  nearest  permanent  water  being  at  least  a quarter 
of  a mile  away.  These  larvae  are  described  as  white  with  pale  brown 
transverse  bands,  and  transform  into  pupae  in  June  or  July,  and  into 
flies  some  two  or  three  weeks  later.  The  earliest  date  on  which  an 
adult  emerged  was  July  4,  which  is  also  the  earliest  date  on  which 
Brimley  has  seen  the  species  in  the  fields.  Two  larvae,  which  had 
been  preserved  in  alcohol,  were  yellower  than  the  trimaculatus  larva 
described  by  Brimley,  but  showed  no  trace  of  the  pale  brown  bands 
which  exist  in  life.  The  largest  of  the  two  measured  36  mm.  long, 
and  was  taken  July  5,  while  the  smaller  one  was  33  mm.,  taken  on 
March  31.  Both,  as  also  the  preserved  trimaculatus  (?)  larva,  were 
well,  but  not  abnormally,  extended. 

The  only  pupa  reported  of  this  species  was  found  by  Brimley  under 
a stone  in  his  back  yard. 

Although  horse-flies  do  not  generally  breed  away  from  water, 
Tabanus  fronto  seems  to  be  an  exception,  as  larvae  have  been  taken  in 


WERNER  MARCHAND 


111 


Brimley’s  garden  in  several  different  years,  while  the  adults  occur 
more  commonly  in  the  garden  and  house  than  any  other  species  of  the 
family,  the  flies  quite  frequently  entering  the  house,  wdiile  newly 
emerged  specimens  have  been  noted  on  a number  of  occasions. 

Tabanus  (Atylotus)19  fulvus  Meigen. — A European  species.  Sharp 
describes  a larva  (Plate  4,  Fig.  60,  a-d ) which  he  says  may  belong  to 
this  species.  This  description  follows: 

“In  a larva,  probably  of  this  family  (Tabanidae),  found  by  the  writer  in  the 
shingle  of  a shallow  stream  in  the  New  Forest  (England),  the  annuli  are  replaced 
by  seven  circles  of  prominent  pseudopods,20  on  the  abdominal  segments,  about 
eigjjt  in  each  circle,  and  each  of  these  feet  is  surmounted  by  a crown  of  small 
hooks,  so  that  there  are  fifty  or  sixty  feet  distributed  equally  over  the  middle 
part  of  the  body  without  reference  to  upper  or  lower  surface.  The  figures  of  the 
larva  of  T.  cordige? , by  Brauer,  and  of  Ilcematopota  pluvialis,  by  Perris,  are  some- 
thing like  this  but  have  no  setae  on  the  pseudopods.” 

Tabanus  fuscipes  Ricardo.— An  African  species  reported  by  Neave 
from  Lake  Chilwa,  southern  Nyasaland,  in  January,  1914,  in  circum- 
stances which  render  it  extremely  probable  that  they  had  bred  in 
mud  some  distance  from  water,  which  had  been  hard  and  dry  for 
some  portion  at  any  rate  of  the  dry  season.  Neave  is  inclined  to 
think  that  in  this  and  other  mid  season  species,  such  as  Tabanus 
claritibialis  Ric.  and  Tabanus  sander soni  Aust.,  the  larvas  hibernate 
fully  fed  at  the  beginning  of  the  dry  season  and  only  pupate  when  the 
next  season’s  rains  release  them  from  the  hard  ground. 

Tabanus  glaucopis  Meigen. — A European  species,  occurring  in 
Austria  as  well  as  in  Scandinavia,  but  evidently  rare.  According  to 
Brauer,  the  larvas  have  been  observed  by  Wahlberg  (1838)  in  noctuid 
caterpillars.  I was  not  able  to  find  the  statement  quoted  by  Brauer, 
but  it  may  be  correct,  as  Wahlberg  made  numerous  observations  on 
parasitic  and  semiparasitic  dipterous  larvae. 

In  as  far  as  most  of  the  Bombyliidae  are  truly  parasitic,  and  tabanid 
larvae  often  burrow  deeply  into  their  prey,  it  is  not  unlikely  that 
tabanids  belonging  to  the  Pangoniinae  which  are  apparently  related 

19  Sharp  (Insects,  p.  483)  uses  the  generic  name  Atylotus , which  is  a subgenus 
of  Tabanus. 

20  Sharp,  like  King,  uses  pseudopod  for  proleg. 


112 


THE  EARLY  STAGES  OE  TABANID^E 


to  the  Bombyliidae,  should  be  of  more  pronounced  parasitic  habits. 
In  Tabanus  glaucopis  we  have  probably  to  deal  with  an  occasional 
parasitism,  not  typical  for  the  species. 

Tabanus  gratus  Loew. — An  African  species,  and,  according  to  Neave, 
a very  common  one  and  one  of  the  earliest  on  the  wing  in  southern 
Nyasaland,  occurring  sometimes  in  August. 

Larvae  and  pupae  were  collected  :n  this  month,  the  first  individual 
emerging  in  the  laboratory  on  September  1.  The  larva  (Plate  3, 
Fig.  51)  is  moderately  pigmented,  though  compared  with  that  of 
T abanus  insignis  the  pigmented  areas  are  nearly  confined  to  the  edges 
of  the  segments  and  are  not  nearly  so  dark  in  color.  The  syphon  is 
somewhat  longer  than  in  that  species.  A few  larvae  were  obtained 
in  the  stream  beds  near  Mt.  Mlanje  and  a small  series  in  Portuguese 
territory  to  the  east  of  the  mountain  early  in  October. 

The  pupal  aster  (Plate  15,  Fig.  186,  a-d ) is  of  the  normal  type, 
being  regular  in  outline.  The  spines  of  the  dorsolateral  comb  are 
much  reduced,  especially  in  the  male. 

Tabanus  hilaris  Walker. — A species  of  Bengal,  Assam,  and  South 
India,  on  the  early  stages  of  which  we  have  some  notes  by  Patton  and 
Cragg  (1913).  According  to  these  authors  its  habits  of  oviposition 
are  the  same  as  in  Tabanus  striatus , that  is,  it  oviposits  as  a general 
rule  on  blades  of  grass,  pieces  of  stick,  etc.,  at  the  edge  of  a river, 
stream,  or  pond.  The  eggs  when  deposited  are  brownish  white. 
No  figures  or  descriptions  are  given. 

Tabanus  ignotus  Rossi. — A species  not  listed  in  Schiner’s  Fauna 
Austriaca,  and,  according  to  del  Guercio,  synonymous  with  Tabanus 
albipes  Fabr.  Del  Guercio  has  given  a somewhat  unsatisfactory 
account  of  its  life  history,  and  its  early  stages.  The  species  has 
appeared,  according  to  del  Guercio,  in  extraordinary  numbers,  in 
company  with  tipulids,  in  the  rice  fields  of  the  region  of  Bologna 
(Italy),  and  the  larva  is  said  by  him  to  have  caused  considerable  dam- 
age to  the  rice  fields. 

The  species,  of  which  del  Guercio  furnishes  a brief  description, 
not  stating,  however,  on  whose  authority  the  insects  were  identified, 
appeared  in  the  region  (Molinella)  from  the  first  ten  to  twenty  days 


WERNER  MARCHAND 


113 


of  June.  The  flies  are  found  on  plants  like  Arum , Sagittaria , Typha , 
etc.,  on  which  they  move  about  frequently  with  a buzzing  sound. 

The  eggs  are  deposited  on  the  leaves  of  the  plants  mentioned  and 
others,  forming  circular  crusts,  which  were  seen  abundantly  after 
oviposition  had  taken  place,  that  is,  during  the  whole  month  of 
July,  while  some  belated  specimens  may  oviposit  as  late  as  August. 
A more  detailed  description  of  egg  or  egg  cluster  is  not  given. 

Larvae  were  never  found  in  the  fall,  but  half  grown  larvae  were  found 
in  winter,  most  of  them  being  ready  to  transform  in  April  or  May  of 
the  following  spring. 

Without  insisting  on  the  strangeness  of  the  fact,  de  Guercio  re- 
ports that  these  larvae  are  so  similar  to  those  of  the  tipulids  found 
by  him  ( Tipula  oleracea  L.)  that  without  an  accurate  examination 
it  would  not  be  possible  to  distinguish  them.  They  are  more  robust, 
more  cylindric,  but  of  the  same  color;  they  are  in  the  same  way  pro- 
vided with  brushes  of  hairs  on  the  segments  of  the  body,  but  the 
mouth-parts  have  mandibles  of  about  twice  the  size  and  thickness  of 
those  of  the  tipulids,  from  which  they  differ  only  by  the  kind  of 
velvety  combs  found  on  the  clypeus  and  in  the  whole  anterior  part 
of  the  head.  The  figure  to  which  del  Guercio  refers,  is  given  (Plate 
7,  Fig.  96,  a,  b)  for  comparison.  The  habits  of  these  larvae  are  said 
to  be  the  same  as  those  of  the  tipulids  with  which  they  are  found, 
and  to  behave  in  the  same  way  when  transforming  into  pupae. 

I have  given  this  description  as  it  is  the  purpose  of  the  present 
report  to  give  a full  account  of  all  that  is  known  about  the  early 
stages  of  Tabanidae.  But  it  may  be  permissible  to  express  a reason- 
able doubt  whether  del  Guercio  did  not  eventually  figure  two  tipulid 
larvae,  having  taken  one  of  them,  erroneously,  to  be  a Tabanus.  As 
no  reference  is  made  to  any  previous  descriptions  of  tabanid  larvae, 
excepting  (see  below)  Tabanus  autumnalis , and  in  this  case  also  the 
literature  is  not  quoted,  and  as  there  is  no  mention  of  the  structures 
common  to  all  known  tabanid  larvae,  as  the  prolegs,  syphon,  respira- 
tory tube,  serrated  mandibles,  the  assertion  that  the  larva  of  this 
Tabanus  can  hardly  be  distinguished  from  that  of  Tipula  oleracea 
cannot  be  taken  seriously. 

The  transformation  takes  place,  according  to  del  Guercio,  from  the 
end  of  May  to  early  June,  when  the  larvae  leave  the  rice  fields  in 
large  numbers  for  their  metamorphosis  in  the  dams  and  meadows. 


114 


THE  EARLY  STAGES  OF  TABANIDiE 


\ 

While  the  Tipula  appears  in  two  generations,  the  life  cycle  of  the 
Tabanus  comprises  only  one  generation,  which  begins  at  the  end  of 
spring  of  one  year  and  is  completed  towards  the  middle  or  end  of 
spring  of  the  following  year. 

The  larva  of  Tipula  and  those  of  Tabanus  are,  as  del  Guercio  in- 
sists, of  the  same  dark  gray  color  as  the  soil  in  which  they  live  and  re- 
semble one  another  not  only  in  shape  but  also  in  many  of  their  organs, 
including  the  mouth-parts,  in  such  a way  that  there  remains  no 
point  of  resemblance,  even  in  this  regard,  between  the  larva  of  the 
Tabanus  of  the  rice  field  and  that,  for  instance,  of  Tabanus  autumnalis , 
the  larvae  of  which  differ  from  it  in  every  detail. 

The  pupa,  however,  is  figured  by  del  Guercio  (Plate  11,  Fig.  123) 
as  the  pupa  of  this  Tabanus , for  comparison  with  the  tipulid  pupa 
(Plate  11,  Fig.  122),  and  is  in  fact  in  every  way  a real  Tabanus  pupa, 
except  that  on  the  figure  no  spiracles  are  visible,  which  were  appar- 
ently overlooked  by  the  author  in  making  the  drawing. 

Del  Guercio’ s statement  that  the  damage  done  by  tipulids  and 
tabanids  in  the  rice  fields  resulted  in  the  destruction  of  the  whole 
cultivation,  has  probably  to  be  corrected  in  that  as  far  as  any  larvae, 
the  tipulids  may  possibly  have  been  responsible  for  the  damage;  for 
the  tabanids,  however,  this  is  very  unlikely,  and,  as  long  as  del 
Guercio  has,  in  fact,  made  no  observations  whatever  on  the  food  of 
his  larvae,  we  are  bound  to  assume  that  the  Tabanus  larvae,  which 
were  apparently  numerous,  but  of  which  we  are  still  awaiting  de- 
scription, fed  on  the  larvae  of  Tipula  oleracea,  and  were  in  this  in- 
stance certainly  not  injurious. 

I wish  here  to  call  attention  to  the  fact  that  Degeer  has  already 
spoken  of  a great  resemblance  between  tabanid  and  tipulid  larvae; 
in  fact,  before  he  knew  that  the  larvae  found  by  him  were  larvae  of 
Tabanus , he  expected  crane-flies  to  hatch.  However,  his  descrip- 
tion, the  first  one  ever  given  of  a Tabanus  larva,  .establishes  beyond 
doubt  the  characteristics  of  these  larvae  by  which  they  differ  from 
those  of  tipulids. 

Tabanus  insignis  Loew. — ( Tabanus  sharpei  Aust.).  An  African 
species,  common  in  southern  Nyasaland,  near  Mt.  Mlanje,  from  No- 
vember to  March. 


WERNER  MARCHAND 


115 


The  very  characteristic  and  strikingly  pigmented  larva  (Plate  3, 
Fig.  53)  was,  according  to  Neave,  common  in  the  mud  of  the  forested 
streams  from  the  end  of  September.  It  may  be  distinguished  at  a 
glance  from  other  similarly  pigmented  species  by  the  white  trefoil- 
shaped area  on  the  dorsum  of  the  anal  segment.  This  is  a voracious 
and  predacious  larva  and  troublesome  to  keep  in  the  laboratory  for 
that  reason. 

The  pupal  aster  is  of  the  normal  type,  the  spines  of  the  dorsolateral 
comb  being  few  in  number  but  somewhat  long.  A small  series  of 
adults  was  bred  by  Neave  from  the  larvag  above  described.  A cer- 
tain number  of  these  flies  belonged  to  the  type  of  Tabanus  sharpei 
Aust.,  and  the  two  forms,  the  larvae  of  which  are  identical,  are  con- 
nected by  a great  variety  of  intermediates. 

The  larva  is  figured  (Plate  3,  Fig.  53),  also  the  pupal  aster  of  the 
male  and  the  dorsolateral  comb  of  both  sexes  (Plate  15,  Fig.  184,  a, 
b,  c).  In  the  figure,  the  larva  looks  much  like  that  of  Tabanus  atratus 
but  the  lateral  stripes  are  poorly  developed  except  on  the  thoracic 
and  on  the  ninth  and  tenth  segments,  while  on  the  eleventh  segment 
they  are  more  completely  fused  with  the  transverse  ones  into  a broad 
pigmented  band. 

Tabanus  kingi  Austen. — Tabanus  kingi,  recorded  from  Khor  Arbat, 
Sudan,  Africa,  is  a species  superficially  resembling  Tabanus  tceniola , 
and  allied  to  species  of  Tabanus  from  Abyssinia  at  present  unde- 
scribed. The  life  history  has  been  worked  out  by  King  (1910),  who 
observed  the  species  in  Khor  Arbat,  in  a locality  consisting  of  a 
stream  of  slightly  brackish  water  running  in  a gorge  on  a rocky  hill. 
On  emerging  from  the  hills  into  the  plain  the  stream  disappears  in 
the  sand.  In  the  autumn,  during  the  brief  rainy  season,  it  comes 
down  in  sudden  overflow,  and  is  then  of  considerable  size,  but  in  April, 
the  month  in  which  these  observations  were  made,  it  is,  except  where 
there  are  pools,  not  more  than  a few  inches  in  depth.  The  bed  of 
the  stream  is  stony  and  there  is  little  or  no  vegetation  on  its  banks. 

The  female  fly  deposits  her  eggs  in  a rounded  mass  on  a rock 
rising  sheer  from  the  water  generally  slightly  overhanging,  and 
from  six  to  fifteen  inches  above  water  level.  Rocks  chosen  for 
this  purpose  overhang  comparatively  deep  pools,  from  eighteen 


116 


THE  EARLY  STAGES  OF  TABANID^E 


inches  upwards,  in  which  the  water  moves  but  slowly.  Such  rocks 
occur  only  here  and  there,  in  the  mile  or  so  of  stream  searched,  only 
three  rocks  bearing  traces  of  having  been  used  by  this  tabanid  for 
purposes  of  oviposition  being  found.  On  one  of  them  were  the  re- 
mains of  several  hundred  egg  masses  lining  a small  crack  in  the  face 
of  the  rock  from  2 to  3^  feet  above  the  water  level.  As  none  of  the 
fresh  egg  masses  found  were  situated  more  than  15  inches  above 
water  level,  these  old  masses  had  probably  been  deposited  when  that 
level  was  higher.  Altogether  seven  females  were  taken  in  the  act  of 
ovipositing,  and  several  more  were  seen.  No  particular  time  of  the 
day  seems  to  be  chosen  for  the  act;  one  was  found  ovipositing  at 
11.40  a.m.  and  another  at  4.40  p.m.,  and  unlike  Tabanus  biguttatus 
Wied.,  the  only  other  horse-fly  King  has  observed  ovipositing  in  the 
field,  this  tabanid  does  not  lose  her  natural  wariness  while  engaged 
in  depositing  her  eggs.  In  fact,  she  is  often  more  difficult  to  capture 
then  than  when  merely  sunning  herself  on  a rock. 

The  egg  masses,  figured  by  King  (Plate  1,  Fig.  20),  vary  in  size,' 
and  no  count  of  the  number  of  eggs  contained  was  made,  but  the 
average  mass  is  believed  to  consist  of  about  500.  When  freshly  laid 
the  mass  is  glistening  white  and  can  be  seen  from  a considerable 
distance,  but  within  a few  hours  it  takes  on  a mottled  gray  hue 
which  so  closely  resembles  the  color  of  the  rock  that  it  is  not  easily 
detected.  While  the  fly  is  occupied  in  laying  her  eggs,  numbers  of  a 
tiny  Hymenoptera  assemble  and  proceed  to  add  their  eggs  to  the 
mass,  continuing  to  do  so  after  the  fly  has  gone.  From  some  twenty 
egg  masses  collected  from  the  rocks  about  equal  numbers  of  this 
egg  parasite  and  of  the  tabanid  larva  were  obtained.  Specimens  of 
these  Hymenoptera  were  sent  for  identification  to  the  Scientific  Sec- 
retary of  the  Entomological  Research  Committee.  They  proved  to 
be  a new  species  of  Chalcidag,  and  have  been  described  by  Mr.  J.  C. 
Crawford,  of  Washington,  under  the  name  of  Telenomus  kingi  (foot- 
note to  King’s  paper,  by  Mr.  Guy  A.  K.  Marshall). 

One  horse-fly21  taken  in  the  act  of  ovipositing  completed  her  egg 
laying  in  a collecting  box  on  the  evening  of  April  13.  These  eggs  had 

21  King  frequently  uses  the  Arabic  word  “seroot,”  for  horse-fly,  by  which  the 
flies  are  known  in  the  Sudan. 


WERNER  MARCIIAND 


117 


hatched  by  the  morning  of  April  19,  the  incubation  period  being  there- 
fore about  five  days.  Under  normal  conditions,  exposed  to  the  sun, 
it  may  possibly  be  less.  The  larvae  from  these  eggs  were  allowed  to 
fall  from  the  egg  mass  into  a basin  containing  water  and  stones  and 
were  provided  with  portions  of  earthworms,  and  tiny  coleopterous 
and  dipterous  larvae  obtained  from  wet  moss.  They  refused  to  feed, 
however,  and  all  died;  probably  at  this  stage  of  their  existence  they 
require  brackish  running  water. 

In  places  the  stream  at  Khor  Arbat  is  very  shallow  and  ripples 
over  and  around  stones;  under  these  stones  larvae  of  various  sizes, 
mostly  nearly  mature,  were  taken.  Apparently  stones  which  were 
not  quite  or  were  barely  covered  with  water  were  chosen  by  the 
larvae  in  order  that  they  might  come  up  to  breathe  without  losing 
their  hold  and  so  be  in  danger  of  being  carried  away  by  the  current. 
Usually  only  a single  larva  was  found  under  one  stone,  and,  in  every 
instance  where  two  or  three  were  together,  a mortal  combat  was 
taking  place.  If  a larva  was  placed  on  one’s  hand  it  would  at  once 
endeavor  to  drive  its  mouth  hooks  through  the  skin,  and  where  the 
skin  was  thin,  it  would  succeed  in  inflicting  a sharp  pricking  pain. 
Owing  to  these  cannibalistic  habits  the  number  of  larvae  which 
could  be  transported  was  restricted  to  the  number  of  vessels  available, 
so,  though  nearly  two  hundred  were  taken  from  the  stream,  only 
forty- two  were  brought  alive  to  Khartoum.  There  they  were  placed 
in  jars  containing  coarse  sand,  brought  from  Khor  Arbat,  and  water, 
and  fed  on  medium  sized  earthworms.  They  took  these  willingly 
when  hungry  but  appeared  to  need  food  only  every  two  or  three 
days.  King  left  Khartoum  on  April  28,  Captain  W.  B.  Fry  taking 
care  of  the  larvae  during  his  absence,  and  on  King’s  return  on  May 
30,  the  majority  of  these  larvae  were  dead.  One,  however,  had  com- 
pleted its  life  cycle  and  seven  were  still  living.  Six  of  these  seven  pu- 
pated during  the  next  few  weeks  but  died  as  pupae.  The  pupal 
period  is  probably  about  six  days,  for  one  which  pupated  on  May  5 
appeared  to  be  mature  on  May  11,  when  it  perished. 

One  empty  pupal  case  was  taken  under  a stone  in  the  bed  of  the 
Khor  Arbat  stream;  the  fly  must  have  crept  up  the  stone  through 
several  inches  of  running  water  before  gaining  the  air. 


118 


THE  EARLY  STAGES  OF  TABANID^E 


Although  this  tabanid,  according  to  King,  in  its  adult  form  closely 
resembles  Tabanus  tceniola  Pal.  de  Beauv.,  in  its  larval  stage  it 
differs  markedly  from  that  species.  The  larva  is  admirably  adapted 
for  clinging  to  stones  in  rapidly  running  water,  its  usually  long  pseudo- 
pods with  strong  hooks,  being  retractile  and  capable  of  being  used 
as  suckers.  None  of  the  other  tabanid  larvae  observed  by  King 
possessed  an  anal  proleg. 

Besides  the  seven  specimens  mentioned  above  as  having  been  taken 
in  the  act  of  ovipositing,  two  more  were  caught  sucking  blood  from 
Camels.  No  males  were  seen. 

King  describes  the  early  stages  in  about  the  following  words. 

Egg. — Length  2 mm.  Color  white,  becoming  darker  as  the  embryo  within 
develops.  Spindle-shaped. 

Mature  Larva. — (Plate  4,  Fig.  56  and  Fig.  65,  a , b,  c.)  Length  35  mm.  Color 
pale  gray  to  dusky  gray  to  deep  chestnut-brown.  Mandibles  dark  brown  to 
black,  long  and  powerful,  slightly  serrated.  Anterior  margins  of  meso-  and  meta- 
thoracic  segments  dark.  A smooth  shiny  pale  area  on  the  dorsum  of  each  thoracic 
segment;  on  the  prothorax  this  area  is  concave  anteriorly,  convex  posteriorly, 
and  with  parallel  sides.  On  the  meso-  and  metathoracic  segments  it  appears  to 
the  naked  eye  diamond-shaped,  though  sometimes  it  is  actually  hexagonal.  On 
the  venter  of  the  prothorax  are  two  shiny  pale  longitudinal  areas,  each  bearing 
several  long  black  hairs  arising  from  a single  pore;  a similar  but  larger  area  is 
striated  on  each  of  the  meso-  and  metathoracic  segments,  bearing  two  similar 
tufts  of  hair.  On  either  side  of  the  meso-  and  metathoracic  segments  are  three 
longitudinal  areas  not  extending  to  the  margins  of  the  segments,  longitudinally 
and  deeply  striated.  On  the  anterior  margins  of  the  meso-  and  metathoracic 
segments  on  either  side  are  four  paler  lines  extending  backwards,  to  form  the 
divisions  and  edges  of  the  three  striated  areas.  On  the  anterior  third  of  each 
abdominal  segment  except  the  eighth  is  a ring  of  pseudopods,  eight  in  each  ring, 
two  dorsal,  two  lateral,  four  ventral,  except  on  the  first  segment,  where  the 
dorsal  pair  is  wanting.  The  dorsal  pseudopods  are  never  well  developed,  and, 
with  the  exception  of  those  on  the  fifth,  sixth,  and  seventh  segments,  unprovided 
with  hooks.  The  lateral  and  ventral  pseudopods  are  very  long  and  bear  at  the 
apcies  long,  strong  hooks,  chestnut-brown  in  color,  sometimes  darker  at  the 
tips.  On  the  median  pair  of  ventral  pseudopods  on  the  fourth,  fifth,  and  sixth 
segments,  these  hooks  form  a complete  circle,  but  on  the  remaining  pseudopods 
bearing  hooks  the  circle  is  incomplete.  Immediately  below  these  hooks  is  a 
row  of  tiny  spines.  Immediately  behind  the  ventral  pseudopods  on  the  first  to 
the  seventh  segments  inclusive  is  a shiny  striated  area.  On  the  venter  of  the 
eighth  segment,  anteriorly  placed  to  the  anus,  is  a pseudopod  equal  in  size  and 
similar  to  the  ventral  pseudopods  on  the  other  segments,  and  bearing  an  incom- 


WERNER  MARCHAND 


119 


plete  circle  of  hooks.  Scattered  over  the  surface  of  the  larva  are  occasional 
black  hairs.  The  syphon,  when  exserted,  is  shorter  than  the  eighth  segment,  and 
bears  a number  of  black  hairs.  The  dark  appearance  of  the  larva  is  due  to  tiny 
dots  of  pubescence  arranged  closely  together,  except  on  the  shiny  areas  mentioned 
above. 

The  skin  of  the  larva  frequently  bears  scars  of  old  wounds. 

Pupal  Case. — (Plate  12,  Fig.  137  a,  b,  c .)  Length  20  mm.  Color  yellowish  brown, 
thoracic  tubercles  and  abdominal  spiracles  darker,  the  former  bearing  hairs.  On 
the  posterior  third  of  the  second  to  the  seventh  abdominal  segments  inclusive 
is  a ring  of  backwardly  pointing  spines,  shortest  on  the  second  segment  and 
longest  on  the  seventh.  The  eighth  segment  terminates  in  a coronet  of  six 
teeth,  chestnut-brown  in  color,  darker  at  the  tips,  the  lateral  pair  by  far  the 
largest,  the  dorsal  and  ventral  pairs  being  equal  in  size.  These  teeth  are  ar- 
ranged roughly  in  a circle.  Ventrally  placed  to  this  coronet  are  two  rows  of 
five  comparatively  thin  spines,  of  varying  length,  together  constituting  an  inter- 
rupted transverse  row.  Dorsolaterally  placed  to  the  coronet  are  two  rows  of 
spines  similar  to  the  ventral  row. 

The  dorsum  of  the  abdomen  is  sometimes  clothed  with  black  pubescence 
arranged  in  four  longitudinal  stripes.  On  the  sixth  and  seventh  segments  these 
stripes  merge  and  on  the  seventh  segment  the  pubescence  is  confined  to  the 
posterior  third.  The  pubescence  is  wanting  on  the  dorsum  of  the  eighth  segment 
but  is  present  on  the  venter  of  the  seventh  and  a small  patch  is  situated  immedi- 
ately below  the  coronet  on  the  eighth  segment. 

The  pupa  when  first  formed  is  yellowish.  Later,  as  the  imago  develops,  the 
eyes  show  as  dark  spots  with  a greenish  tinge  and  the  thorax  becomes  generally 
darker. 

Tabanus  lasiophthalmus  Macquart. — This  species,  which  is  widely 
spread  and  occurs,  according  to  Time,  in  eastern  North  America, 
Columbia,  and  Chile,  has  been  reared  by  Hine  (1906)  from  the  egg 
to  the  adult.  The  fly  is  one  of  the  earliest  of  the  genus  to  appear  in 
the  spring,  adults  having  been  taken  at  Columbus,  Ohio,  as  early  as 
May  20,  and  it  is  common  during  the  first  half  of  June.  The  eggs  are 
placed  in  masses  on  various  plants  that  grow  in  low,  wet  ground,  but 
Hine  has  not  observed  them  over  water.  The  masses  are  shiny 
black  when  fully  colored,  rather  small  for  members  of  the  genus, 
only  slightly  convex,  and  accompanied  with  an  unusual  amount  of 
cementing  material,  which  nearly  obscures  the  form  and  arrange- 
ment of  the  individual  eggs.  The  mass  suggests  somewhat  a drop  of 
tar  or  other  black  substance  fastened  to  the  surface  of  a leaf  of  the 
common  cattail  reed  ( Typha  latifolia) , a sedge,  or  some  other  plant. 


120 


THE  EARLY  STAGES  OF  TABANIDiE 


The  eggs  are  usually  deposited  after  June  10,  and  the  specimens 
from  which  larvae  for  rearing  hatched  were  taken  in  Medina  County, 
Ohio,  on  a common  sedge  found  growing  near  the  outlet  of  a small 
spring.  They  were  collected  June  28  and  hatched  the  next  day  and 
the  day  after.  As  Hine  had  not  been  successful  up  to  this  time  in 
keeping  very  young  larvae  for  any  length  of  time,  it  was  decided  to 
try  different  methods  of  treatment  in  order  to  find  out,  if  possible, 
that  which  is  best  suited  to  their  requirements.  Some  were  placed 
in  a jar  containing  water  only  (No.  1) ; others  in  a jar  containing  water 
with  a couple  of  inches  of  sand  in  the  bottom  (No.  2).  A third  jar 
(No.  3),  in  which  larvae  were  placed,  contained  wet  muck,  while  the 
fourth  lot  (No.  4)  was  placed  in  a jar  containing  moist  sand  to  the 
depth  of  about  3 inches,  covered  over  the  top  with  a quantity  of  fine 
leaves  of  water  plants.  In  all  the  breeding  jars  were  placed  plenty 
of  small  crustaceans  and  other  minute  invertebrates  procured  from 
water  by  means  of  a finely-meshed  sieve. 

It  was  soon  observed  that  the  larvae  in  breeding  jar  No.  4 fed  on 
the  crustaceans,  and  at  the  end  of  a few  days  showed  a distinct  in- 
crease in  size.  Those  in  the  jars  containing  water  soon  died,  and  jar 
No.  3 did  not  appear  to  be  a success,  so  all  but  No.  4 were  aban- 
doned. The  larvae  in  this  last,  however,  were  separated,  and  placed 
in  similar  jars,  one  specimen  in  each,  and  reared  to  full  size,  the 
adult  fly  being  procured  the  following  spring. 

Since,  as  stated,  three  of  the  four  jars  started  were  soon  abandoned, 
what  is  said  hereafter  regarding  the  method  used  in  rearing  pertains 
to  the  single  one  retained.  A glass  jar  was  selected  so  that  the 
actions  of  the  larvae  could  be  observed;  a small  jar  seemed  desirable 
because  the  larvae  are  predacious  and  eat  their  own  kind  as  readily 
as  anything  else,  for  which  reason  it  is  necessary  after  a short  time 
to  place  only  a single  specimen  in  a jar;  also,  even  a small  receptacle 
furnishes  plenty  of  room  and  the  long  series  which  it  is  desirable  to 
have  takes  as  much  space  in  the  insectary  as  one  cares  to  give  to  a 
single  species.  Only  the  quantity  of  sand  and  other  material  neces- 
sary to  success  should  be  placed  in  the  breeding  jar,  as  it  is  desirable 
once  in  a while  to  look  this  material  over  carefully  in  order  to  locate 
the  very  small  specimens  and  find  out  what  they  are  doing. 


WERNER  MARCHAND 


121 


Half  pint  jelly  glasses  were  found  by  Iiine  to  be  well  suited  for  the 
purpose  and  easily  obtainable.  Covers  proved  to  be  desirable  in 
order  to  prevent  too  rapid  evaporation  of  moisture,  but  a small  per- 
foration or  two  in  them  was  necessary  to  furnish  ventilation.  As  the 
muck  which  was  tested  as  soil  for  the  jars  grew  much  mold,  clean  lake 
sand  was  chosen  as  decidedly  preferable  for  the  purpose.  The  cov- 
ering of  plant  material  mentioned  furnished  a resting  place  for  the 
small  crustaceans  offered  for  food,  and  the  larvae  themselves  seemed  to 
choose  to  remain  in  it  in  preference  to  burrowing  into  the  sand,  al- 
though they  were  apt  to  be  found  in  any  part  of  the  jar.  Algae  made 
good  material  for  covering,  but  only  a small  amount  could  be  used, 
and  too  much  water  was  detrimental  as  either  in  excess  tended  to 
cause  decay,  and  consequently  a bad  odor,  which  was  observed  to  be 
unfavorable  to  the  insects.  The  principal  point  in  favor  of  the  algae 
was  that  they  contained  no  hollow  stems  or  large  pieces  into  which 
the  larvae  could  crawl,  but  still,  being  composed  of  small  soft  par- 
ticles, furnished  a mat  in  which  they  could  hide.  When  it  was  de- 
sired to  locate  these  larvae  it  was  easily  done  by  picking  the  mass  to 
pieces.  As  odors,  which  are^  often  fatal  to  the  larvae,  were  likely  to 
develop  from  the  material  put  in  for  food  and  also  from  other  sources, 
it  was  found  necessary  to  watch  the  jars  continually,  giving  them  a 
thorough  cleansing  once  in  a while,  and  perhaps  putting  in  fresh  sand 
and  plant  material  occasionally. 

Larvae  when  first  hatched  were  about  2 mm.  in  length;  they  grew 
rather  slowly,  but  in  fifteen  days  after  hatching  had  doubled  their 
length.  They  fed  readily  on  the  small  crustaceans  which  were  given 
them.  It  was  impossible  to  give  these  small  crustaceans  their  proper 
surroundings,  so  many  of  them  died,  and  it  was  observed  that  the 
young  larvae  fed  on  these  as  well  as  on  t be  specimens  which  they 
killed  themselves.  The  larvae  could  be  seen  crawling  about  in  the 
jars;  they  appeared  to  remain  very  near  the  upper  surface  of  the 
sand  most  of  the  time,  and  when  food  was  scarce  did  much  crawling, 
but  when  food  was  plentiful  satisfied  their  appetites  and  hid  among 
the  plant  material  where  they  remained  quiet. 

A difference  in  size  in  the  various  larvae  soon  became  apparent,  and 
the  older  they  became  the  greater  was  this  difference.  On  July  23, 
twenty-five  days  after  hatching,  some  specimens  measured  as  much 


122 


THE  EARLY  STAGES  OF  TABANIDiE 


as  7 mm.,  while  others  measured  only  3 mm.  At  this  date  angle- 
worms  were  given  for  food,  and  were  accepted  readily,  and  appeared 
to  be  as  satisfactory  as  the  crustaceans,  but  it  would  seem  that  the 
latter  are  preferable  for  the  stage  just  after  hatching. 

On  July  27  some  of  the  larvae  were  10  mm.  in  length,  and  on  August 
2 the  same  specimens  measured  12  mm.;  thus  at  this  stage  they  grew 
more  rapidly  than  when  they  were  younger.  They  fed  actively  till 
about  the  middle  of  September,  when  they  had  become  apparently 
full  grown,  or  25  mm.  long.  Length  in  the  larvae  of  tabanids  is,  ac- 
cording to  Hine,  not  a satisfactory  means  of  indicating  the  size,  for 
the  segments  telescope  on  one  another  in  such  a way  that  it  is  difficult 
to  take  two  measurements  exactly  alike,  but  an  endeavor  was  made 
in  this  case  to  make  the  different  measurements  similar,  so  I believe 
that  those  given  are  considered  sufficient  to  indicate  the  comparative 
sizes  of  the  different  ages.  After  September  15  the  few  specimens 
remaining  alive  buried  themselves  in  the  sand  of  the  breeding  jars 
and  were  quiet  most  of  the  time  until  March  10,  when  one  pupated, 
the  adult  emerging  on  the  25th  of  the  same  month.  The  others  died 
before  the  pupal  stage  was  reached.  Hine  has  noted  that  larvae  of 
various  species  of  tabanids  taken  from  their  natural  habitats  during 
the  winter  did  not  produce  adults  in  the  spring  much  before  the 
same  species  appeared  naturally,  but  in  this  case,  where  the  specimens 
was  kept  under  artificial  conditions  during  its  entire  life,  the  adults 
appeared  almost  two  months  earlier  than  is  normal  in  nature. 

Hine’s  description  of  the  larva  follows: 

uThe  mature  larva  [Plate  3,  Fig.  44]  is  not  notably  different  from  those  of 
other  species  of  Tabanus  so  far  as  form  and  appearance  are  concerned.  The  color 
is  a dirty  white  with  a pinkish  shade  over  most  of  the  body;  the  prolegs  are  not  so 
prominent  as  in  many  species,  and  on  this  account  specimens  appear  somewhat 
maggot-like.  On  either  side  of  the  body  is  a longitudinal  row  of  very  small  black 
spots  or  specks,  one  to  each  segment  and  located  just  above  the  ventral  pro- 
legs; these  spots  are  lacking  on  some  of  the  anterior  and  some  of  the  posterior 
segments;  their  presence  appears  to  be  characteristic  of  the  species,  at  least  so  far 
as  my  acquaintance  with  different  larvae  goes.  Mature  specimens  are  about  25 
mm.  in  length.” 

Hine  has  not  taken  the  larva  of  this  species  in  its  natural  habitat, 
therefore  he  cannot  say  where  it  is  to  be  found,  but  he  thinks  that 


WERNER  MARCHAND 


123 


it  lives  in  debris,  or  in  the  ground  around  low  places  near  where  the 
eggs  are  laid.22 

“ The  pupa  [Plate  1 1,  Fig.  127]  is  somewhat  dusky  in  coloration,  the  thorax  being 
almost  black.  The  terminal  teeth  of  the  abdomen  [Plate  13,  Fig.  159]  are  quite 
different  from  those  of  any  species  studied  so  far,  and  these  differences  alone 
make  its  determination  easy.  The  dorsal  and  lateral  teeth  are  much  larger  than 
the  ventral,  the  lateral  being  much  larger  than  any  of  the  others;  the  ventral 
teeth  point  almost  directly  backward,  while  the  direction  of  the  others  is  largely 
upward.  The  thoracic  spiracle  is  rather  small  and  nearly  longitudinal,  its  rima 
is  curved,  but  no  distinct  hook  is  formed  at  the  posterior  end.  Length  18  mm.” 

We  owe  our  knowledge  of  the  early  stages  of  Tabanus  lasiophthalmus 
entirely  to  Hine. 

Tabanus  laverani  Surcouf. — An  African  species,  being  rare  in  Neave’s 
locality,  Mt.  Mlanje  in  southern  Nyasaland,  where  only  occasional 
specimens  were  taken. 

A single  female  was  bred  on  November  25,  1913,  from  a larva  col- 
lected near  Neave’s  headquarters.  The  larva  did  not  belong  to  the 
pigmented  type  like  that  of  Tabanus  grains  and  resembled  the  larva 
of  Tabanus  variabilis  in  bearing  lateral  prolegs  on  the  anal  segment. 
It  was,  however,  of  a yellower  color  and  less  transparent  than  that 
species,  and  lacked  any  pigmentation  on  the  syphon. 

The  pupal  aster  (Plate  15,  Fig.  185,  a)  is  remarkable  for  the  great 
size  and  elongation  horizontally  of  the  middle  pair  of  hooks.  The 
dorsolateral  comb  is  reduced  to  two  very  short  processes,  the  main 
combs  on  the  last  segment  being  also  of  this  character,  as  may  be 
seen  from  the  view  in  profile. 

The  pupal  aster  and  dorsolateral  comb  of  the  female  are  figured 
(Plate  15,  Fig.  185,  a,  b,  c). 

Tabanus  lineola  Fabricius. — A common  species,  inhabiting  eastern 
North  America,  common  in  states  as  wide  apart  as  Massachusetts, 
Ohio,  New  Jersey,  and  Louisiana. 

We  owe  to  Hart  a description  of  larva  and  pupa.  The  larva  closely 
resembles  the  young  of  nigrescens , and  was  not  separated  from  it  at 
first.  Examples  were  taken  at  Hart’s  collecting  station,  C,  near  the 

22 1 have  since  found  (May,  1917)  the  larva  of  this  species  in  the  muddy  bank 
of  a rapid  flowing  brook  in  the  neighborhood  of  Princeton,  N.  J. 


124 


THE  EARLY  STAGES  OF  TABANID^E 


foot  of  Quiver  Lake,  Illinois,  over  sand,  mud,  and  algae  vegetation; 
at  Station  I,  in  the  bed  of  the  slough  with  grass,  rushes,  and  willows, 
and  a very  shallow  stream  of  spring  water  when  the  river  is  low ; and 
at  Station  H,  on  the  Illinois  River  below  Havana,  Illinois,  where  it  is 
narrow,  (the  east  bank  steep  and  sandy,  a layer  of  mud  over  sand  at 
lower  levels,  the  water  quickly  deepening,  considerable  current,  a 
little  vegetation;  on  the  west  bank  mud,  steeply  sloping,  trees  but 
almost  no  vegetation,  decided  current),  on  April  14,  15,  and  30; 
and  in  Flag  Lake,  (shallow,  muddy,  bordered  with  rushes,  thick  with 
floating  vegetation),  on  April  27 — as  shown  by  specimens  preserved. 
The  larvae  were  also  taken  April  8 and  June  15  and  24  in  Sand  Lake, 
Lake  County,  Illinois,  and  in  ponds  in  Kane  and  Champaign  Counties. 

I give  Hart’s  description  of  the  larva. 

“Larva. — Length  20  mm.,  diameter  2.7  mm.  Prothorax  with  lateral  shining 
areas  about  as  long  as  the  dorsal  area,23  striation  about  the  same  as  that  of  the 
upper  mesothoracic  area,  no  noticeable  central  smooth  spot,  a small  one  on  the 
lower  margin  posteriorly;  remaining  lateral  areas  a little  more  finely  and  closely 
striate;  dorsal  and  ventral  areas  of  thorax  nearly  smooth  on  disk,  with  basal 
striae;  those  of  abdomen  with  moderately  close  striae,  more  or  less  interrupted  on 
disk;  all  areas  more  or  less  shining.” 

“ Surface  whitish,  dull  pubescent  markings  very  light  brown  but  distinct,  annuli 
narrow,  crests  of  false  feet  also  dull  pubescent,  their  sides  striate;  lateral  stripes 
of  thorax  distinct,  slender,  not  dilated  posteriorly,  lateral  edges  of  dorsal  areas 
of  thorax  diverging.  An  opaque  dark  ring  about  base  of  respiratory  tube,  and 
another  encircling  anal  prominence,  above  it  usually  three  light  brown  spots.” 

“Main  internal  tracheae  rather  thick  and  noticeable,  subparallel,  not  strongly 
sinuate,  at  least  back  of  the  middle.  Terminal  stigmatal  spine  often  protruded.” 

Of  Tabanus  lineola  Hart  has  obtained  three  pupae  on  May  18  of 
different  years.  Imagos  were  obtained  from  these  on  May  27,  29, 
and  June  6.  The  tabanid  pupae  develop,  according  to  Hart,  much 
more  rapidly  in  hot  weather  than  in  cold,  and  to  this  fact  is  probably 
due  the  difference  in  time  of  emergence.  Another  pupa  was  taken  at 
Matanzas  Lake  on  August  24.  Hart’s  description  of  the  pupa  follows: 

“Pupa. — [Plate  12,  Fig.  149;  Plate  13,  Fig.  162.1  Length  19  mm.,  diameter  3 
mm.  Light  ferruginous  brown,  shining,  abdomen  roughly  wrinkled  and  sub- 

23 1 cannot  confirm  this  character  from  material  collected  in  Princeton,  Spring, 
1917. 


WERNER  MARCHAND 


125 


opaque.  Palpal  sheaths  indistinct,  not  distant;  tubercles  not  dark;  ocellar  tuber- 
cles indistinct  or  wanting;  thoracic  spiracular  tubercles  slightly  but  nearly  equally 
elevated,  free  margin  rounded  at  tip,  rima  not  vertical,  evenly  arcuate,  slightly 
hooked  in  front.” 

“Abdominal  spiracular  tubercles  subtriangular,  narrower  behind,  obliquely 
subconical,  much  shorter  than  basal  diameter,  bearing  a small  subcircular  or  short 
and  strongly  arcuate  rima;  on  anterior  slope  a transverse  groove,  usually  longer 
than  the  rima;  fringes  formed  of  unequal  pale  spines,  only  one  or  two  long  spines 
above  on  seventh  segment;  outer  terminal  teeth  much  longer  than  the  others, 
directed  laterally  and  upwards,  the  tips  of  the  four  upper  teeth  about  in  line. 
Fringe  anterior  to  anal  prominence  showing  a chitinous  webbing  between  the 
bases  of  the  spines,  so  that  the  separated  tufts  of  the  female  look  like  a pair  of 
broad  low  teeth  with  several  spiny  points;  lateral  tufts  low  down,  near  ends  of 
ventral  fringe,  formed  of  short  spines.” 

The  pupa  is  also  figured  by  Malloch  (from  Hart’s  material),  (Plate 
12,  Fig.  149). 

Oviposition  and  eggs  are  not  known.  Also  it  remains  to  be  deter- 
mined whether  there  are  one  or  two  broods  of  this  species  in  one 
year.  Adults  were  taken  as  early  as  May  17,  and  as  late  as  September 
27,  with  dates  of  capture  in  June,  July,  and  August. 

Tabanus  maculatissimus  Macquart. — An  African  species  com- 
mon in  the  neighborhood  of  Mt.  Mlanje,  southern  Nyasaland,  where 
Neave  obtained  data  on  the  early  stages. 

The  larvae  were  found  in  mud  in  a partially  dried  up  stream,  and 
from  these  a few  individuals  of  the  adult  were  bred  during  Novem- 
ber. The  larvae  were  obtained  in  Portuguese  territory  to  the  east  of 
Mt.  Mlanje.  These  larvae  were  not,  however,  at  the  time  distin- 
guished from  those  of  Tabanus  biguttatus , of  which  they  were  thought 
to  be  immature  examples.  The  figure  (Plate  5,  Fig.  71)  is  from 
other  individuals,  obtained  subsequently,  which  are  believed  by 
Neave  to  belong  to  this  species.  This  figure  shows  the  pigmentation 
pattern  of  the  eleventh  segment  considerably  developed,  while  the 
dark  circular  band  at  the  posterior  end  of  the  segment  is  compara- 
tively narrow. 

The  pupal  aster  (Plate  14,  Fig.  178,  c)  is  normal  except  for  a pa- 
pilla on  each  side  of  the  middle  line,  about  the  middle.  There  is  a 
well  marked  dorsolateral  comb,  consisting  of  comparatively  short 
stout  spines.  The  pupal  aster  and  dorsolateral  comb  of  the  female 


126 


THE  EARLY  STAGES  OF  TABANIDiE 


and  the  dorsolateral  comb  of  two  different  male  individuals  are  fig- 
ured (Plate  14,  Fig.  178,  a-d). 

Tabanus  medionotatus  Austen. — An  African  species,  to  which  Neave 
attributes,  with  some  doubt,  a series  of  specimens  collected  in  southern 
Nyasaland  in  1915.  Of  this  species  five  males  and  three  females 
were  bred  between  the  end  of  September  and  the  beginning  of 
November. 

The  pale  colored  larva  has  rather  long  prolegs,  a ring  of  pigment  of 
varying  width  around  the  base  of  the  syphon  (Plate  5,  Fig.  68),  and 
another  ring  around  the  anus,  which  is  usually  prominent  in  the 
living  larvae.  There  are  also  present  two  prolegs  immediately  ante- 
rior to  the  anus,  but  these  are  not  visible  in  the  somewhat  contracted 
preserved  specimen  and  therefore  are  not  shown  in  the  figure.  The 
pupal  aster  (Plate  14,  Fig.  174,  a , b)  resembles  that  of  Tabanus 
obscuripes  in  having  a large  and  even  longer,  but  less  horizontal, 
middle  pair  of  hooks.  Not  only  the  dorsolateral  but  also  most  of 
the  lateral  comb  is  absent. 

Tabanus  melanoceros  Wiedemann. — A species  recorded  from  the 
Atlantic  States  from  New  Jersey  south. 

Late  in  March,  1909,  Brimley  in  Raleigh,  North  Carolina,  found, 
while  looking  under  stones  in  a small  clear  woodland  stream,  a 
Tabanus  larva  which  was  quite  lively  and  seemed  thoroughly  at  home 
in  clear  water.  He  kept  the  specimen  in  a bottle  with  some  wet  leaves 
and  practically  forgot  it.  However,  on  May  18  it  had  transformed 
to  a pupa,  and  thirteen  days  later,  on  May  31,  a male  of  Tabanus 
melanoceros  emerged  from  the  pupa.  The  larva  was  approximately 
the  same  size  as  the  trimaculatus  larvas  collected  by  Brimley,  and  was 
like  them  white  without  darker  bands; 

Tabanus  nagamiensis  Carter. — An  African  species,  only  recently 
described,  of  which  a single  female  was  captured  by  Neave  on  the 
Malosa  River,  the  Anglo-Portuguese  boundary  south  of  Mt.  Mlanje, 
southern  Nyasaland,  on  October  8,  1913.  A male  was  bred  from  a col- 
lected pupa  on  September  27,  1913. 

The  pupal  aster  (Plate  15,  Fig.  179,  a , b)  somewhat  resembles  that 
of  Tabanus  laverani  in  the  great  development  of  the  middle  pair  of 


WERNER  MARCHAND 


127 


hooks,  the  dorsolateral  comb  is  absent,  a characteristic  which  Neave 
has  not  seen  in  the  pupa  of  any  other  species  of  Tabanus , except  in 
Tabanus  medionotatus . The  other  combs  are,  however,  striking  and 
characteristic,  as  may  be  seen  from  the  figure. 

Tabanus  nigerrimus  Zetterstedt. — Of  this  European  species  we  have 
some  indication  that  it  is  lignicole  in  its  larval  stage.  Scholtz  (1850) 
expresses  the  opinion  that  perhaps  some  Tabani  live  in  their  early 
stages  in  the  detritus  of  old  tree  trunks.  He  found,  in  July,  1848,  in  a 
deep  wooded  ravine  near  Chari ottenbrunn,  on  the  decaying  trunk  of 
a tree  of  Fagus  sylvatica , a newly  hatched  but  already  fully  colored 
specimen  of  Tabanus  nigerrimus  Zett.,  which  had  previously  been 
found  in  Sweden  and  Norway. 

Tabanus  nigrescens  Palisot  de  Beauvois. — This  species  is  nearly 
related  to  Tabanus  stygius,  occurring  in  the  Atlantic  States  (New 
Jersey),  and  also  in  Illinois.  Of  its  oviposition  nothing  is  known, 
but  Hart  has  observed  the  larva  and  given  us  a description  of  the 
pupa. 

An  undersized  larva,  supposed  to  belong  with  those  of  stygiust 
pupated  May  18,  and  on  June  1 produced  an  imago  of  Tabanus 
nigrescens.  Most  of  the  larvae,  treated  in  Hart’s  paper  as  stygius 
were  very  uniform  in  size  and  characteristics;  Hart,  though  unable 
to  separate  the  two  species  at  this  stage,  believes  that  the  bulk  of 
his  material  at  least  was  stygius.  The  imago  of  nigrescens  had  been 
taken  previously  near  the  Mississippi,  in  southern  Illinois,  on 
August  10. 

“Pupa,  Male. — Length  25  mm.,  diameter  5.5  mm.  Palpal  sheaths  narrowly 
separated,  about  one  fourth  as  far  apart  as  the  setae  borne  by  the  large  frontal 
tubercles,  a smooth  depressed  space  between  them,  without  tubercles.  Lobes 
of  carinate  transverse  ridges  of  head  more  rounded  and  separated  by  a deeper 
notch  than  usual.  Abdomen  a little  more  shining  and  more  smoothly  wrinkled. 
Otherwise  not  different  from  the  pupa  of  stygius  (female)  next  described.” 

From  Malloch’s  analytical  table  the  following  data  are  obtained 
on  the  pupa: 

“Pupa. — Dorsal  abdominal  segments,  four  to  six  at  least,  with  one  or  two 
transverse  series  of  short  irregular  spines,  the  bases  of  which  are  not  much  dilated, 


128 


THE  EARLY  STAGES  OF  TABANID^E 


and  slightly  caudad  of  these  is  a transverse  series  of  closely  placed,  very  long, 
slender  bristles.  Length  at  least  25  mm.;  abdominal  spiracles  with  very  much 
elongated  vertical  rima,  the  upper  and  lower  extremities  slightly  curved  forward. 
The  long  spines  on  dorsal  abdominal  segments  either  black-tipped  or  all  pale, 
without  a black  preapical  ring;  short  spines  in  anterior  dorsal  series  slender  and 
very  uneven.  A small  but  distinct  tubercle  just  in  front  of  base  of  middle  leg  in 
addition  to  and  some  distance  above  the  one  bearing  the  paired  hairs.” 

Malloch’s  material,  which  was  partly  the  same  as  that  collected 
by  Hart  in  1895,  contained  only  one  specimen  of  nigrescens  (in  very 
poor  condition). 

The  prothoracic  spiracle  of  the  pupa  has  been  figured  by  Malloch 
(Plate  13,  Fig.  156). 

Tabanus  obscuripes  Ricardo. — An  African  species,  occurring  in 
southern  Nyasaland,  chiefly  on  the  plains  in  Portuguese  territory  to 
the  east  and  south  of  Mt.  Mlanje,  in  October  and  November. 

A single  male  was  bred  by  Neave  from  a pupa  collected  on  Octo- 
ber 1.  The  pupal  aster,  which  is  figured  (Plate  15,  Fig.  183,  a,  b) 
somewhat  resembles  that  of  Tabanus  laverani  and  has  the  same  large 
middle  pair  of  hooks.  The  dorsolateral  comb  is  reduced  to  a single 
knob-like  process. 

Tabanus  ( Neotabanus )24  ochrophilus  Lutz. — A common  Brazilian 
species.  On  its  early  stages  we  possess  some  notes  by  Lutz  in  Rio  de 
Janeiro  (1914). 

Larvae  of  this  species  were  found  in  muddy  or  sandy  soil  below  and 
at  the  sides  of  a small  brook  with  slowly  flowing  water.  Large 
quantities  of  sand  had  to  be  sifted  to  obtain  them.  As  food,  tubi- 
fex  was  given.  The  full  grown  larvae  measured  30  mm.  Color 
creamy  white,  integument  shining  and  transparent,  intestine  reddish 
or  blackish.  Tracheae  silvery.  Mandibles  dark,  serrate  beneath. 
Digestion  slow,  four  to  five  days.  Before  pupation,  contracted;  in 
spontaneous  death,  expanded. 

Culture  in  moist  sand,  but  for  observation  purposes  moss  in  glass 
jars  was  preferred.  The  larvae  have  to  be  kept  in  the  dark  during  the 
intervals  of  observation.  The  pupal  stage  lasted  about  ten  days. 

24  The  few  species  of  Neotabanus  of  which  early  stages  are  known  are  here  class- 
ified with  Tabanus.  There  is  no  doubt  that  the  genus  Tabanus  could  be  subdi- 
vided into  smaller  genera  or  subgenera  but  opinions  on  this  point  are  not  definite. 


WERNER  MARCHAND 


129 


The  eyes  change  color  after  two  or  three  days.  Eye  coloration  and 
stripes  of  abdomen  visible  two  to  three  days  before  hatching.  Pupal 
shell  very  transparent. 

Tabanus  orientis  Walker. — A Tabanus  occurring  in  North  India, 
Nepal,  Bhutan,  particularly  in  high  elevations;  according  to  Baldrey, 
“ by  far  the  largest  of  the  species  caught  at  Muktesar  (7,500  feet); 
it  is  caught  at  the  beginning  of  March  and  appears  then  to  be  quite 
full  grown  (owing  to  its  torn  and  worn  out  condition).” 

According  to  Baldrey,  who  tried  to  breed  the  species  for  experi- 
mental purposes,  it  begins  laying  its  eggs  during  the  last  weeks  in 
April,  and  all  flies  dissected  up  to  June  19  were  found  full  of  eggs. 

The  eggs  when  first  laid  are  of  a creamish  white  color,  but  after  a 
few  hours  this  changes  to  a cigarette-ash  color.  They  are  laid  in 
batches  resembling  bunches  of  bananas. 

Four  lots  of  eggs  were  found  in  jars  containing  flies;  in  two  cases 
the  only  fly  in  the  jars  was  found  dead. 

Tabanus  par  Walker. — Of  this  African  species  we  possess  full  de- 
scriptions of  the  egg,  larval,  and  pupal  stages  by  King  (1910),  who 
not  only  secured  oviposition  in  captivity,  but  also  bred  the  species 
through  from  the  egg  to  the  adult  stage. 

Occasional  specimens  of  this  tabanid  were  met  with  on  the  White 
Nile  from  Gebelein  southwards.  In  the  country  behind  Bor  females 
were  abundant  and  seemed  to  spend  their  time  resting  on  foliage, 
waiting  for  approaching  animals  which  they  would  attack  at  once. 
No  eggs  could  be  found,  though  a careful  search  was  made  in  all 
the  places  that  were  considered  likely  to  serve  as  breeding  grounds; 
hence  a number  of  females,  gorged  with  blood,  were  placed  in  a 
breeding  cage,  in  which  was  also  a dish  containing  mud,  water,  and 
growing  grass  and  weeds.  The  flies  fed  on  sugar  and  water,  and 
though  the  majority  died  within  the  first  two  days,  the  survivors 
eventually  produced  three  small  batches  of  eggs  (Plate  1,  Fig.  10). 
The  eggs  obtained  in  this  manner  were  deposited  on  May  23  and  24, 
on  the  under  sides  of  the  leaves  of  a water  weed.  Unlike  the  eggs  of 
most  members  of  the  genus  Tabanus,  they  were  not  closely  packed 
in  a rounded  mass,  but  placed  vertically  and  separately  though  in  a 


130 


THE  EARLY  STAGES  OF  TABANH)^ 


cluster.  The  single  egg  is  “ spindle-shaped,  about  1.15  mm.  in  length 
and  white  in  color,  becoming  darker  as  the  embryo  within  develops.” 

The  eggs  obtained  hatched  on  May  30,  consequently  after  an  incu- 
bation period  of  six  to  seven  days,  and  the  tiny  larvae  (Plate  1,  Fig. 
11)  were  divided  into  three  lots,  and  placed  in  glass  basins  containing 
mud,  water,  and  growing  grass.  These  basins  for  purposes  of  refer- 
ence were  labelled  A,  B,  and  C.  At  the  time  when  the  eggs  hatched, 
King  was  in  the  Sudan  region,  where  it  was  impossible  to  land  and 
obtain  any  subterraneous  insect  larvae  or  tiny  fresh  water  crustaceans 
for  them,  'so  they  were  offered  the  expressed  stomach  contents  of 
gorged  female  ticks — Rhipicephalus  simus — taken  from  a dog.  A 
few  fed  once  or  twice  but  the  majority  refused,  and  all  buried  them- 
selves in  the  mud. 

On  June  1 1 , the  larvae  from  A were  transferred  from  mud  to  clean 
river  sand  and  water,  and  given  freshly  killed  mosquito  larvae.  They 
fed  on  these  readily  and  grew  apace,  though  at  greatly  varying  rates. 

The  larvae  in  B were  also  given  mosquito  larvae  from  June  11,  but 
they  refused  to  feed,  and  the  mud  in  which  they  were  living  was  sev- 
eral times  allowed  to  dry  up.  On  July  11  they  were  placed  in  clean 
river  sand  and  water,  and  at  once  began  to  feed  and  grow. 

On  July  19,  when  King  returned  to  Khartoum,  their  diet  was 
changed,  owing  to  the  difficulty  of  obtaining  mosquito  larvae,  to 
freshly  killed  and  bruised  earthworms.  They  did  not  take  readily 
to  this  food,  and  some  died,  while  others  disappeared  from  the  basins. 
At  the  time  it  was  thought  that  they  had  become  cannibals,  but 
eventually  it  was  found  that  they  were  being  taken  by  mice.  The 
stock  of  larvae  from  A and  B had  by  this  time  become  reduced  to 
one,  which  appeared  to  be  full  grown  and  so  was  killed  and  preserved. 

On  July  26  the  larvae  from  C were  transferred  to  clean  river  sand 
and  water.  It  was  then  fifty-seven  days  since  they  had  emerged 
from  eggs,  and  they  had  spent  a great  part  of  that  time  in  a dry 
cake  of  mud.  Occasionally  this  mud  had  been  moistened,  and  food 
offered  them,  but  they  had  very  rarely  taken  it.  Most  of  them  were 
alive,  but  with  the  exception  of  a few  which  were  slightly  larger  than 
when  just  hatched,  they  had  not  grown  at  all.  They  now  under 
more  favorable  conditions  fed  readily  on  a mixed  diet  of  earthworms 
and  mosquito  larvae  and  grew,  some  rapidly,  others  more  slowly. 


WERNER  MARCHAND 


131 


On  September  3 and  4 one  pupated,  lying  on  the  surface  of  the  sand, 
partly  submerged  in  water,  and  six  days  later  gave  rise  to  an  adult 
female.  By  October  18  several  more  had  completed  their  life  cycles, 
and  on  that  date,  as  King  was  proceeding  to  England  on  leave,  the 
remaining  ones  were  killed  and  preserved. 

All  those  that  pupated  did  so  on  the  surface  of  the  sand,  some  high 
and  dry,  others  half  in  and  half  out  of  the  water.  “Probably,”  says 
King,  “ under  more  natural  conditions,  the  pupal  stage  would  be 
passed  buried  in  the  soil — -the  structure  of  the  pupal  case  seems  to 
indicate  this.” 

The  average  pupal  period  was  from  six  to  eight  days. 

The  following  are  practically  King’s  descriptions  of  larva  and  pupa 
(that  of  the  egg  having  been  quoted  previously)  of  Tabanus  par. 

The  mature  larva  (Plate  3,  Fig.  48)  when  fully  extended  measures  about  13.5 
mm.  Color  white  with  a grayish  tinge.  Mandibles  dark  brown  to  black,  ser- 
rated. On  the  anterior  third  of  each  abdominal  segment  except  the  eighth  is  a 
ring  of  pseudopods,  eight  in  each  ring — two  dorsal,  two  lateral,  and  four  ventral — 
except  on  the  first  abdominal  segment,  where  the  two  dorsal  ones  are  wanting. 
On  the  second  abdominal  segment  the  two  dorsal  pseudopods  are  very  small. 
The  pseudopods  are  largest  on  the  third,  fourth,  and  fifth  abdominal  segments, 
and  are  always  more  developed  on  the  ventral  than  on  the  dorsal  surface.  Each 
pseudopod  bears  a crown  of  colorless  spines  or  hooks,  and  there  are  patches  of 
dark  spines  between  the  pseudopods.  The  spines  on  the  dorsal  sections  of  the 
rings  on  the  first  and  second  abdominal  segments  are  dark.  The  anus  is  situated 
ventrally,  at  the  base  of  the  eighth  segment,  and  is  fringed  with  blackish  hairs. 
The  syphon  tube  consists  of  two  segments,  and,  when  exserted  is  as  long  as  the 
eighth  abdominal  segment. 

The  pupa  (Plate  12,  Fig.  142,  a,  b)  is  from  12  mm.  to  15  mm.  in  length  and 
at  first  yellowish  white  in  color,  becoming  darker  as  it  nears  maturity.  The  eyes 
show  plainly  through  the  pupal  case  as  dark  greenish  purple.  The  empty  pupal 
case  is  yellowish  brown,  the  thoracic  tubercles  and  the  spiracles  being  darker 
than  the  surrounding  parts.  On  the  apical  third  of  the  second  abdominal  seg- 
ment is  a fine  ring  of  backwardly  pointing  spines.  Similar  but  broader  rings, 
bearing  longer  and  stronger  spines,  are  on  the  third,  fourth,  fifth,  and  sixth 
abdominal  segments,  and  one  of  intermediate  breadth  on  the  seventh.  The 
eighth  abdominal  segment  terminates  in  a coronet  of  six  teeth,  in  color  shining 
brown,  becoming  darker  at  the  tip.  The  dorsal  pair  are  smallest  and  close  to- 
gether, the  ventral  pair  next  in  size  and  wider  apart,  and  the  lateral  pair  longest 
and  arising  from  almost  the  same  level  as  the  dorsal  pair.  Ventrally  placed  to 
this  coronet  of  teeth  are  two  rows  of  small  teeth,  from  two  to  four  in  each  row, 


\ 


132  THE  EARLY  STAGES  OF  TABANIDiE 

together  forming  an  interrupted  transverse  row.  These  teeth  are  of  unequal  size 
and  vary  in  their  relative  size  in  different  specimens. 

Tabanus  pertinens  Austen.— An  African  species,  according  to  Neave 
usually  confined  to  comparatively  low-lying  country  where  the  river 
beds  are  of  a sandy  nature.  In  southern  Nyasalalid  it  was  found  com- 
mon on  the  Mwanza  River,  in  the  Shire  Valley,  as  early  as  the  end  of 
July,  but  did  not  occur  on  Mt.  Mlanje,  though  a few  specimens  were 
taken  by  Neave  at  some  distance  from  the  mountain. 

A pigmented  larva  (Plate  3,  Fig.  54),  which  it  was  thought  might 
belong  to  this  species,  was  taken  in  some  numbers  in  the  Shire  River 
in  August,  and  in  the  Ruo  River  in  October.  It  was  found  in  both 
cases  in  water  amongst  the  roots  of  grasses  or  water  plants,  and 
seems  to  prefer  rivers  with  a sandy  bottom  and  banks.  The  striking 
larva  is  remarkable  for  the  development  of  the  dorsal  prolegs,  which 
perhaps  are  associated  with  its  comparatively  free-swimming  exist- 
ence. The  prolegs  are  also  present  immediately  anterior  to  the  anus. 

Tabanus  quatuornotatus  ( quadrinotatus ) Meigen. — Common  in 
Europe.  This  was  the  first  species  of  tabanid  in  which  the  eggs  and 
the  act  of  oviposition  became  known.  The  credit  of  the  discovery  is 
due  to  Joseph  Mann,  Curator  of  the  Imperial  and  Royal  Zoological 
Cabinet  in  Vienna,  who,  according  to  Kollar’s  report  in  1854,  during 
a naturalist’s  trip  to  Carniola,  Austria,  in  May  and  June,  1854,  suc- 
ceeded in  observing  in  a damp  meadow  at  Wippach  the  female  of 
Tabanus  quatuornotatus  in  the  act  of  oviposition.  Mann’s  own  words, 
quoted  by  Kollar,  are  translated  as  follows: 

On  June  25  at  11  a.m.,  I found  a Tabanus  just  beginning  to  deposit  eggs  on  a 
grass  blade;  as  it  did  not  attempt  to  escape,  I cut  off  the  blade  and  took  it  home. 
Towards  2 p.m.  the  Tabanus  flew  to  the  window;  I at  once  looked  at  the  grass 
blade  and  found  on  it  a cluster  of  eggs  completed.  These  were  wax-yellow  at 
first,  later  on  they  took  on  a grayish  color,  and  two  days  afterwards  they 
appeared  almost  black. 

Mann  later  on  found,  in  the  field  and  also  on  other  plants,  several 
egg  masses  similar  to  the  first,  bringing  them  all  to  Vienna. 

By  this  discovery  it  was  known  for  the  first  time  that  the  Tabanus 
does  not  deposit  the  eggs  on  the  ground  where,  according  to  Degeer, 
the  larva  lived,  but  on  plants;  further,  that  the  Tabanus  does  not 


WERNER  MARCHAND 


133 


scatter  its  brood  as  many  other  species  of  flies  do,  but  deposits  the 
eggs  in  a single  mass. 

The  eggs  were  counted,  and  their  number  found  to  be  about  350 
to  400.  Also  the  hatching  of  young  larvae  was  observed,  and  the 
duration  of  the  egg  stage  found  to  be  from  ten  to  twelve  days  (Kollar). 

From  the  egg  masses  collected  by  Mann,  besides  young  Tabanus 
larvae,  also  ichneumonid  flies  (parasitic  Hymenoptera)  were  observed 
to  hatch;  to  Kollar  and  Mann  consequently  credit  is  to  be  given  for 
the  first  discovery  of  hymenopterous  egg  parasites  in  tabanids, 
though  no  description  is  given  (see  under  Parasites  of  the  early 
stages  of  Tabanidae,  page  182). 

The  publication  of  Kollar  has  been  quoted  in  detail  by  Lecaillon,  to 
whom  we  owe  further  studies  on  the  early  stages  of  Tabanus  quat- 
uornotatus , chiefly  on  the  oviposition  of  this  species.  Lecaillon 
found  the  species,  with  a related  form,  Tabanus  bromius , abundantly 
at  Gouy,  Aisne,  France,  in  May,  1904.  Oviposition  of  Tabanus 
quatuornotatus  was  observed  on  May  24,  1904.  In  the  afternoon  of 
a sunny  day,  on  a wooded  and  not  especially  damp  hillside,  a female 
was  found  sitting  immobile  on  a dry  branch  of  a weed  {Origanum) , 
the  head  turned  downwards,  at  a distance  of  35  to  40  cm.  from  the 
ground.  The  eggs  already  laid  formed  a conspicuous  white  mass. 
On  coming  nearer,  Lecaillon  ascertained  that  the  Tabanus , which 
under  every  other  circumstance  is  likely  to  take  flight,  was  not  dis- 
turbed and  continued  to  oviposit.  Lecaillon  broke  off  the  branch 
with  the  insect  on  it,  placing  the  whole  in  a jar.  The  female  con- 
tinued to  oviposit  for  about  ten  minutes,  when  it  ceased  and  left 
the  branch.  The  egg  has  been  figured  by  Lecaillon. 

Lecaillon  calls  attention  to  the  fact  that,  as  already  stated  by 
Kollar,  the  ovipositing  female  is  somehow  indifferent  to  what  is 
going  on  around  her,  a fact  which  should  be  taken  into  account  in 
understanding  the  habits  of  adult  tabanid  flies. 

Concerning  the  early  stages,  we  learn  from  Lecaillon’ s observations 
on  this  species  that  oviposition  in  some  tabanids  may  take  place  in 
comparatively  dry  and  not  necessarily  in  a damp  environment.  In 
both  Mann’s  and  Hart’s  observations  it  took  place  in  a moist  environ- 
ment. As  among  insects  frequently  not  only  the  necessities  of  em- 
bryonal but  also  of  larval  life  may  be  anticipated  from  the  manner 


134 


THE  EARLY  STAGES  OF  TABANID^E 


and  conditions  of  oviposition,  Lecaillon  thinks  that  as  in  tabanids 
oviposition  may  take  place,  according  to  species,  either  in  a dry  or 
in  a damp  locality,  “not  only  the  embryo  but  also  the  larva”  can  live 
under  very  variable  conditions  of  humidity.  Lecaillon  considers  that 
observations  on  the  larval  life  of  Tabanus  quatuornotatus  verify  this 
hypothesis. 

Later,  in  1905,  again  large  numbers  of  egg  masses  of  this  species 
were  found  by  Lecaillon,  and  his  first  observations  could  be  generalized 
to  some  extent.  The  eggs  were  always  laid  on  warm  sunny  days 
in  early  June  about  the  middle  of  the  day,  and  almost  without  ex- 
ception on  dried  out  twigs  of  various  herbaceous  plants.  In  fact,  of 
sixty  egg  masses  collected  in  1905,  not  a single  one  was  found  on  a 
green  leaf  or  stem.  During  the  subsequent  years,  few  exceptions  to 
this  rule  were  noticed.  In  1907,  however,  Lecaillon  found  an  egg 
cluster  fastened  to  a green  stem  of  a grass,  and  in  1908  a cluster  fas- 
tened to  the  dry  branch  of  a tree  (bouleau)  which  had  been  rammed 
into  the  ground.  Lecaillon  discusses  (1906)  this  fact,  putting  the 
question  whether  we  might  be  dealing  with  mimetic  resemblance. 
This  he  thinks  hardly  probable.  The  females,  avoiding  the  green 
objects,  would  alight  only  on  twigs  of  grayish  or  blackish  color.  More 
likely  it  seems  to  Lecaillon  that  the  females  oviposit  on  dry  twigs 
because  these  are  more  rigid  than  the  green  stems.  In  fact,  it  is 
observed  that  during  the  act  of  oviposition,  the  stems  of  weeds  on 
which  the  insects  alight  are  curved,  especially  when  agitated  by  the 
wind.  On  the  dried  out  twigs  the  Tabanus  is  in  a much  more  stable 
situation  and  can  with  greater  facility  give  to  the  egg  mass  its  rather 
complicated  form.25 

The  places  where  eggs  had  been  deposited  were  in  all  cases  exam- 
ined on  woody  slopes  distant  from  any  water  courses.  This  fact 
alone  is  certainly  sufficient  to  prove  that  the  larvae  of  Tabanus 
quatuornotatus  are  not  aquatic  but  terrestrial. 

The  egg  masses  are  found  in  large  numbers  assembled  in  certain 
places  on  hillsides  which  evidently  present  all  the  favorable  conditions 
to  which  the  ovipositing  females  are  adapted.  This  circumstance  is 

25  Lecaillon’s  explanation  is  more  than  doubtful.  Many  species  of  tabanids 
complete  their  egg  masses  on  quite  slender  reeds  and  grasses.  Also  for  Tabanus 
quatuornotatus  it  remains  doubtful  by  what  stimuli  it  is  attracted  to  the  twig. 


WERNER  MARCHAND 


135 


favorable  to  the  destruction  of  the  eggs  in  the  case  of  very  dangerous 
species  which  should  be  brought  under  control.  The  egg  masses  are 
in  fact  very  conspicuous  and  may  be  collected  easily  and  quickly. 
All  egg  masses  observed  were  placed  about  30  to  50  cm.  above  the 
ground. 

The  latest  date  on  which  oviposition  was  observed  was  June  14; 
however,  it  may  be  that  it  takes  place  even  later,  as  Lecaillon  found 
eggs  containing  larvae  as  late  as  July  22  (1907).  The  period  of  re- 
production extends  in  this  species,  at  least  in  certain  years,  from  the 
end  of  May  to  the  end  of  June.  The  period  given  in  Lecaillon’s 
note  in  1906,  of  two  to  three  weeks,  was  evidently  too  short. 

A detailed  description  of  the  egg  mass  is  given  (Plate  2,  Figs.  33 
to  38).  The  egg  mass  presents  the  aspect  of  a roughly  subconical 
body  which  under  natural  conditions  is  placed  with  the  base  below  and 
the  vertex  above.  The  axis  of  the  cone  is  arranged  about  parallel  to 
the  branch  or  stem  which  serves  as  support,  and  is  placed  in  such  a 
way  as  to  cut  lengthwise  through  the  conical  surface  and  to  be  partly 
enveloped  by  it.  However,  it  would  not  be  accurate  to  speak  of  the 
egg  mass  as  subconical,  as  certain  authors  (Brauer  and  Hart)  have 
done.  The  body  of  the  mass  is  distinctly  bilaterally  symmetrical, 
as  shown  in  the  accompanying  figures.  The  plane  of  bilateral  sym- 
metry is  determined  by  the  stem  which  serves  as  a support  and  by  a 
crested  longitudinal  line  placed  on  the  side  opposite  the  egg  mass 
(Plate  2,  Figs.  34  and  35).  On  the  other  hand,  it  is  possible,  with 
regard  to  the  mass,  to  distinguish  a vertical  direction  or  orien- 
tation, a horizontal  anteroposterior  one,  following  the  plane  of  sym- 
metry, and  a horizontal  lateral  one,  placed  at  right  angles  to  this 
plane.  In  the  anteroposterior  direction  the  base  of  the  mass  has  its 
greatest  dimension  (5  mm.  in  a specimen  examined).  In  the  two 
other  directions  the  dimensions  are  about  the  same  and  somewhat 
smaller  than  in  the  preceding  one.  Posteriorly,  the  surface  adhering 
to  the  support  is  much  larger  than  the  opposite  surface  anteriorly. 
Finally,  in  the  specimens  examined,  the  base  of  the  mass  was  not 
flat  but  perceptibly  and  progressively  excavated  from  the  periphery 
towards  the  center. 

The  egg  mass  is  composed  of  eggs  which  are  placed  quite  regularly 
on  top  of  each  other,  if  observed  vertically,  or  placed  in  successive 


136 


THE  EARLY  STAGES  OF  TABANID^E 


horizontal  layers,  if  observed  horizontally.  The  eggs  are,  moreover, 
glued  together  by  a substance  which  hardens  after  deposition,  and 
causes  the  eggs  to  adhere  strongly  to  each  other.  It  goes  without 
saying  that  the  number  of  eggs  contained  in  a horizontal  layer  dimin- 
ishes if  we  proceed  from  the  base  of  the  mass  towards  its  summit. 

The  color  of  the  egg  mass,  which  is  white  at  the  moment  of  deposi- 
tion, is  changed  rapidly  into  brown  and  later  into  black.  The  change 
of  coloration  begins  some  time  after  oviposition  is  completed;  it  ap- 
pears at  first  at  the  summit  of  the  mass,  thence  it  spreads  towards  its 
base,  which  after  a few  hours  has  turned  almost  completely  dark 
brown  or  black.  This  change  of  coloration  in  the  egg  masses  of  taba- 
nids  has  already  been  observed,  as  Lecaillon  emphasizes,  by  Mann 
and  also  by  Hart.  However,  Mann,  who  observed  the  same  species 
as  that  studied  by  Lecaillon,  speaks  of  a wax-yellow  color  which  later 
passes  into  blackish  brown,  and  Lecaillon  assumes  that  Mann  has  not 
noticed  the  primitive  white  color  of  the  eggs  when  first  laid,  or  that  he 
possibly  dealt  with  a different  species.  Hart’s  statement  that  in  the 
eggs  of  Chrysops  nicer ens  (cestuans)  the  first  color  is  cream,  seems  bet- 
ter to  agree  with  Lecaillon’ s observation.  This  may  possibly  be 
merely  an  inexactness  of  terms,  as  one  author  may  call  an  object 
white  which  another  would  call  pale  yellow  or  cream. 

The  change  of  coloration  which  takes  place  in  the  egg  mass  a 
short  time  after  oviposition  must  be  considered  as  advantageous,  as 
we  have  to  deal  with  the  substitution  of  a protective  color  (black) 
for  a white  color  which  as  actually  observed,  renders  the  eggs  very 
conspicuous  to  the  eye. 

According  to  Lecaillon,  the  color  of  insect  eggs  may  be  due  either 
to  a coloration  of  the  yolk,  or  to  a coloration  of  the  egg  envelopes. 
Changes  of  coloration  can  consequently  be  due  to  changes  taking  place 
inside  the  egg,  or  to  changes  taking  place  in  the  envelopes.  In  the 
case  of  Tabanus  quatuornotatus , the  substitution  of  the  white  color 
by  a dark  color  is  due  to  a brown  pigment  which  develops  in  the 
chorion  after  oviposition,  probably  by  the  slow  effect  of  air  and 
light.  This  pigment  is  very  strongly  developed  and  hides  com- 
pletely the  contents  of  the  egg.  Consequently  even  at  the  end  of 
embryonic  development  when  the  eggs  contained  wholly  white 
larvae,  they  still  are  in  external  appearance  completely  black. 


WERNER  MARCHAND 


137 


The  pigment  is,  according  to  Lecaillon,  not  altered  by  alcohol, 
while  in  eggs  in  which  the  color  is  due  to  the  yolk  the  latter  is  usually 
decolorized  by  the  action  of  alcohol. 

The  female  constructs  its  egg  mass,  depositing  the  eggs  one  after 
the  other,  beginning  at  the  anterior  end.  At  last,  when  the  mass 
has  reached  a certain  width  the  eggs  are  found  arranged  in  horizontal 
and  more  or  less  regular  layers,  while  the  lower  border  of  the  mass 
forms  a pronounced  projection,  the  beginning  of  the  depression  of 
the  lower  surface.  While  the  female  is  sitting  with  head  turned 
downwards  the  tip  of  the  abdomen  is  placed  upwards,  towards  the 
point  where  the  egg  is  to  be  laid. 

The  eggs  themselves  are  of  curved  shape,  they  measure  about  2.5 
mm.  in  length  and  only  0.5  mm.  in  width.  Their  convex  side,  which 
is  chiefly  visible  in  those  which  lie  at  the  periphery  of  the  egg  mass, 
is  always  directed  towards  the  outer  side  of  the  latter. 

Lecaillon  calls  attention  to  the  significant  regularity  of  tabanid  egg 
masses.  Among  the  greater  part  of  insects  which  deposit  their  eggs 
freely  on  leaves,  twigs,  walls,  etc.,  the  egg  mass  consists  generally  of 
an  agglomeration  of  any  shape  which  it  may  assume  under  the  con- 
ditions presented  by  the  object  on  which  the  eggs  are  laid.  In 
Tabanus  quatuornotatus , however,  the  case  is  different;  the  egg  mass 
has  a very  complicated  structure,  which  to  a great  extent  is  inde- 
pendent of  the  shape  of  the  supporting  object,  and  of  a strictly  bi- 
lateral symmetry  which  can  certainly  be  regarded  as  a characteristic 
of  evolutionary  perfection.  From  Hart’s  figures  it  is  seen  that  the 
same  character  is  found  also  in  the  egg  mass  of  T dbanus  atratus  and 
Chrysops  cestuans  (mcerens) ; and  it  is  probably  generally  found 
among  tabanids. 

In  a later  paper,  in  1911,  Lecaillon  reports  additional  observations 
made  on  this  species  in  1906,  1907,  and  1908,  on  the  conditions  un- 
der which  the  eggs  are  laid,  and  a more  amplified  description  of  the 
egg  masses  themselves. 

Since  the  first  publication,  a considerable  number  of  egg  masses  of 
Tabanus  quatuornotatus  were  examined  and  a number  of  individual  dif- 
ferences were  found  in  the  arrangement  of  the  egg  masses.  Some  of 
the  more  interesting  forms  met  with  were  figured  in  the  plate  added 
to  the  second  publication.  The  egg  mass  previously  described  is 


138 


THE  EARLY  STAGES  OF  TAB  ANTE)  iE 


consequently  incomplete;  moreover,  they  are  found  frequently  in 
places  where  this  Tabanus  oviposits.  But  in  many  cases  the  egg 
masses  have  been  found  to  be  much  larger  than  the  one  described  in 
1905.  In  cases  where  the  egg  mass,  fastened  to  a twig,  reaches  its 
maximum  of  development,  it  is  much  more  prolonged  vertically 
than  the  one  figured  in  Lecaillon’s  first  report,  and  it  possesses  a 
second  plane  of  symmetry  which  is  horizontal  and  at  right  angles  to 
the  principal  plane  of  symmetry  passing  through  the  stem  which 
serves  as  support  and  through  the  anterior  tip  which  presents  the  egg 
mass.  But  only  rarely  will  the  egg  mass  be  found  entirely  com- 
pleted in  this  manner,  and  all  the  intermediate  forms  are  found 
between  that  described  in  the  first  publication  and  that  described 
later,  with  two  planes  of  symmetry. 

Frequently  the  egg  masses  are  found  grouped  together  on  the  same 
stem,  numbering  two,  three,  or  four  (Plate  2,  Figs.  35  to  38). 

Finally,  as  stated  also  in  Lecaillon’s  short  note  of  1906,  two  egg 
masses  are  frequently  not  only  contiguous  but  actually  form  the 
continuation  of  each  other  (Plate  2,  Fig.  33).  Of  these  joint  egg 
masses  Lecaillon  is  uncertain  whether  they  are  produced  by  one 
female  or  by  two  different  females.  Probably  the  latter,  inasmuch  as 
in  the  figures  given  their  size  is  considerable;  also  from  our  knowledge 
of  the  egg-laying  instinct  of  the  female,  it  does  not  discern  between 
the  eggs  laid  by  itself  and  eggs  laid  by  another;  consequently  it  will 
be  likely  to  continue  the  process  of  oviposition  started  by  another 
female  in  case  it,  by  chance,  had  alighted  on  a stem  where  already 
other  females  were  laying.  As  during  the  process  of  laying  the 
single  egg  is  always  placed  beside  another  previously  laid,  one  would 
expect  that  in  starting  an  egg  mass,  preference  would  be  given  to  a 
place  where  eggs  are  already  present  instead  of  places  where  only  a 
smooth  surface  is  given. 

Sometimes  the  herbaceous  stem  which  supports  the  egg  mass  is 
very  fine,  and  in  these  instances  the  latter  surrounds  it  almost  com- 
pletely, even  from  behind,  following  the  median  line  of  the  stem. 
In  other  cases  the  egg  mass  is  attached  to  the  top  of  the  spike  of 
grass  plant;  in  this  instance  it  envelops  only  a small  part  of  the 
object,  so  that  from  behind  the  egg  mass  appears  as  of  considerable 
width. 


* 


WERNER  MARCHAND 


139 


Besides,  the  egg  masses  are  never  found  of  a strictly  geometrical 
form,  and  numerous  irregularities  in  details  of  their  structure  are 
always  observed.  In  general,  however,  it  can  be  said,  that  the  eggs 
are  placed  horizontally  and  in  rows  which  when  observed  horizontally 
or  vertically  always  present  a more  or  less  regular  arrangement. 

On  the  larval  stage  of  this  species  we  possess  the  results  of  Lecail- 
lon’s first  studies  (1905),  amplified  by  later  additions.  At  the  time 
of  Lecaillon’ s studies  knowledge  about  tabanid  larvae  was  still  very 
meager;  he  believes  that  the  larvae  are  predacious,  and  there  are 
certain  species  which  are  aquatic  and  others  in  which  the  larva  lives 
in  the  ground  or  in  moist  soil. 

Lecaillon  made  an  attempt  to  raise  the  larvae  of  Tabanus  quat - 
uornotatus  from  the  egg,  but  did  not  succeed  completely,  as  many  of 
the  larvae  died  in  spite  of  all  precautions;  but  he  was  able  to  keep 
them  alive  for  several  months  and  some  of  them  were  still  living  when 
the  paper  was  published  (December  15,  1905),  having  survived  for 
more  than  six  months.  Lecaillon  made  some  observations  on  the 
hatching  of  the  larvae. 

According  to  Mann,  the  duration  of  embryonic  development  in  this 
species  is  ten  to  twelve  days.  Lecaillon  placed  eggs  laid  May  24  in  a 
moderately  damp  atmosphere  (the  stem  with  the  eggs  was  simply 
placed  in  a crystallizing  dish),  and  observed  that  on  June  6,  thirteen 
days  after  oviposition,  no  hatching  had  taken  place.  Taking  two 
eggs  out  of  the  mass,  he  saw,  as  a result  of  the  slight  pressure  or 
traction  to  which  they  had  been  submitted,  the  hatching  of  com- 
pletely developed  larvae. 

On  the  following  day  the  egg  mass  was  vigorously  rubbed,  and 
as  a result  all  the  larvae  hatched  at  once,  showing  that  embryonic 
development  had  been  completed  in  all  the  eggs.  The  difference  in 
time  appearing  in  Lecaillon’ s observation  as  compared  with  that  of 
Mann  is  said  to  have  no  significance  as  the  duration  of  embryonic 
development  is  very  variable,  in  a given  species,  according  to  the 
temperature  in  which  the  eggs  are  kept. 

The  medium  duration  of  embryonic  development  was,  according  to 
Lecaillon’s  first  publication,  from  twelve  to  thirteen  days.  But 
later  he  found  that  the  larvae  generally  do  not  hatch  as  soon  as  they 
are  completely  developed;  they  may  remain  inside  the  egg  shells  for 


140 


THE  EARLY  STAGES  OF  TABANIDiE 


a period  which  seems  to  be  rather  long.  In  1907,  Lecaillon  found 
that  eggs  which  were  laid  on  June  11  had  not  yet  hatched  on  June  8. 
Eggs  collected  on  July  11,  which  had  certainly  been  laid  a long  time, 
produced  larvae  on  July  22.  Embryonic  development  is,  however, 
completely  terminated  at  the  end  of  twelve  or  thirteen  days,  be- 
cause, after  that  period,  it  is  sufficient  to  rub  the  egg  mass  only 
slightly  in  order  to  cause  the  larvae  to  hatch. 

It  can  be  assumed,  consequently,  that  the  larvae  do  not  leave  the  egg 
shells  in  which  they  have  developed,  until  they  need  food;  from  the 
time  of  their  formation  to  that  of  hatching,  they  probably  find  an 
efficient  protection  inside  the  egg  shells.  Perhaps  also  the  egg  shell 
which  has  to  be  pierced  by  the  larvae  in  the  act  of  hatching  is  of  a vari- 
able resistance  according  to  the  conditions  of  the  environment.  In 
a damp  environment,  for  instance,  the  shell  would  be  less  resistant 
than  in  a dry  atmosphere,  and  the  larvae  could  hatch  much  more 
easily  in  the  first  than  ijL  the  second  instance.  The  larva  appears  in 
this  case  to  be  adapted  to  remaining  enclosed  in  the  chorion  of  the 
egg  for  a time  long  enough  to  wait  for  favorable  atmospheric  condi- 
tions. Lecaillon  has  not  made  exact  studies  to  determine  this  point. 

Wheh  the  larvae  hatch,  they  remain  sometimes  for  a few  moments 
on  the  surface  of  the  egg  mass.  They  carry  out  very  varied  move- 
ments of  contraction  and  finally  fall  to  the  ground  into  which  they 
burrow  immediately.  Often  they  are  also  attached  to  one  another, 
forming  sort  of  batches  which  finally  lose  hold  on  the  egg  mass  and 
fall  to  the  ground.  They  are,  as  Lecaillon  says  in  1906,  extremely  luci- 
fugous  (negative  phototropic),  and  they  could  not  be  easily  destroyed. 

Immediately  after  hatching,  the  larvae  are  white  in  color  and  this 
color  is  retained.  The  body  is  also  somewhat  transparent,  and  the 
arrangement  of  different  internal  organs  can  be  observed  with  facility. 
It  is  seen  that  in  the  middle  intestine  there  remains  a rather  large 
quantity  of  nutritive  yolk,  a remainder  of  the  primitive  egg  contents. 
At  the  level  of  the  yolk  the  intestinal  tract  is  opaque.  When  placed 
in  damp  earth,  the  young  larvae  appear  not  to  take  food  for  several 
days. 

In  order  to  ascertain  whether  these  larvae  were  carnivorous,  Le- 
caillon supplied  them  with  ant  nymphae  freed  from  their  cocoons, 
with  flies  killed  previously,  and  with  larvae  of  Chironomus.  He 


WERNER  MARCHAND 


141 


found  that  they  did  not  attack  these  with  great  alacrity,  but  seemed 
rather  to  avoid  their  contact  when  placed  near  them.  However, 
after  having  pierced  Chironomus  larvae  by  means  of  a pointed  scalpel, 
Lecaillon  observed  some  of  the  larvae  to  suck  up  the  blood,  their  in- 
testinal tract  assuming  a characteristic  red  color;  he  even  saw  them 
penetrate  into  the  body  of  the  animal  in  order  to  devour  it.  On  the 
other  hand,  it  was  observed  that  the  larvae  placed  in  moist  earth  ab- 
sorbed the  organic  detritus,  giving  their  intestine  a distinct  dark 
color.  These  facts  led  Lecaillon  to  assume  that  the  larvae  of  Tabanus 
quatuornotatus  can  feed,  according  to  circumstances,  on  animal  or 
vegetable  matter  in  process  of  decomposition,  and  probably  also  on 
certain  soft  larvae  selected  by  the  experimenter. 

Lecaillon  goes  on  to  investigate  the  conditions  of  humidity  favor- 
able for  the  larvae.  Generally  he  left  them  in  very  moist  earth.  But 
once,  having  placed  within  the  crystallizing  dish,  which  contained  the 
larvae,  another  dish  the  under  side  of  which  was  wet  and  rested  on  the 
former,  from  which  the  earth  had  been  partly  removed,  Lecaillon  found 
that  fifteen  larvae  had  assembled  under  the  smaller  dish,  between  the 
two  glass  surfaces,  and  were  completely  submerged  in  water.  He 
subsequently  placed  a number  of  larvae  in  a cup  filled  with  water, 
and  observed  that  they  appeared  to  be  at  home  in  the  water,  remain- 
ing in  it  and  making  no  attempt  to  leave  it.  Later,  Lecaillon  placed 
the  larvae  which  he  intended  to  rear  in  mud  taken  from  an  aquarium; 
they  remained  completely  burrowed  in  this  mud  and  could  even  find 
nourishment  in  it. 

On  the  other  hand,  Lecaillon  repeatedly  allowed  the  earth  in  which 
larvae  were  kept  to  dry  out  completely  and  found  that  the  larvae  not 
only  did  not  suffer  but  remained  quite  active. 

His  conclusion  was  that  the  larvae  of  Tabanus  quatuornotatus  are 
capable  of  adapting  themselves  to  a variable  degree  of  humidity,  and 
can  live,  at  least  for  some  time,  in  dry  ground  as  well  as  in  water. 
Concerning  the  range  of  humidity,  and  also  concerning  food  habits, 
these  larvae,  as  probably  other  tabanid  larvae  also,  appear  not  to  be 
adapted  to  limited  conditions,  in  contrast  to  many  other  insects. 

In  his  later  publication,  Lecaillon  emphasizes  the  great  resistance 
of  the  larvae  of  Tabanus  quatuornotatus  to  humidity  and  draught,  ex- 
plaining the  fact  by  the  presence  on  the  body  surface  of  a chitinous, 


142 


THE  EARLY  STAGES  OF  TABANIDiE 


thick,  and  impermeable  integument.  In  acetic  sublimate,  at  a tem- 
perature of  24°,  the  larvae  remain  alive  for  more  than  half  an  hour. 
It  may  be  mentioned  that  many  dipterous  larvae  behave  in  this  rela- 
tion exactly  like  the  larvae  of  tabanids. 

Lecaillon  has  again  tried  to  rear  larvae  of  this  species  which  had 
hatched  on  June  27,  1905.  He  found  that  they  succeed  best  in  moist 
ground.  In  February,  1906,  a rather  large  number  of  these  larvae 
were  still  alive;  they  had  grown  comparatively  little,  measuring  only 
7 or  8 mm.  in  length,  against  2 or  3 mm.  at  the  time  of  their  birth. 
Some  lived  for  a year  without  having  reached  a much  greater  size 
than  this.  Some  of  the  larvae  were  still  found  alive  in  July,  1906. 

Under  the  conditions  mentioned,  the  intestinal  tract  of  the  larvae 
almost  always  contains  particles  of  soil,  giving  them  a blackish  color. 

From  these  observations  it  is  probable  that  in  Tabanus  quatuorno- 
tatus  the  duration  of  the  larval  stage  is  more  than  one  year.  However, 
Lecaillon  believes  that  this  need  not  necessarily  be,  as  it  is  apparent 
that  the  larvae  when  kept  in  moist  earth  do  not  find  exactly  the  con- 
ditions under  which  they  live  in  nature.  Their  growth  is  consequently 
much  diminished  and  cannot  be  compared  with  normal  growth. 
This  subject,  however,  requires  further  investigation. 

The  chitinous  cuticle  of  the  larva  was  also  studied  by  Lecaillon 
(1906).  It  is  thick  and  resistant,  as  generally  in  dipterous  larvae. 
Its  thickness  in  a larva  of  630  /x  in  diameter  being  about  17  /x.  This 
resistant  and  impermeable  covering  protects  the  larva  efficiently. 
It  may  be  left  in  the  water,  for  instance,  for  several  hours  without 
being  appreciably  injured.  It  can  be  left,  on  the  other  hand,  in  dried 
soil  for  a considerable  time  without  being  killed.  If  one  wishes  to 
fix  the  larvae  in  toto,  even  in  the  case  of  very  small  larvae,  great  diffi- 
culties are  encountered  because  of  the  impermeability  of  the  chitinous 
membrane. 

The  free  surface  of  the  chitinous  layer  appears  to  the  unaided  eye 
to  be  smooth  and  devoid  of  hairs.  But  with  a lens  it  is  found  that  it 
presents  numerous  longitudinal  parallel  ridges  and  numerous  hairs  of 
reduced  length.  This  characteristic  has  been  found  to  be  a general 
feature  of  tabanid  larvae,  and  the  examination  of  the  striae  can  fur- 
nish the  means  to  distinguish  the  genera  and  species. 


WERNER  MARCHAND 


143 


The  finer  structure  of  the  chitinous  layer  is  easily  studied  on  cross 
sections  of  the  larva  which  is  fixed  and  stained  before.  On  section 
the  chitinous  layer  is  found  to  consist  of  three  zones;  first,  an  inner' 
zone,  which  is  in  immediate  contact  with  the  hypothelium;  second,  a 
median  zone,  resting  on  the  former;  third,  an  external  zone,  which 
limits  the  body  of  the  larva  exteriorly.  These  three  zones  present 
different  characteristics. 

1.  The  inner  zone  is  highly  developed;  it  is  much  thicker  than  the 
two  other  layers  taken  together.  It  is  of  a lamellar  structure,  as  on 
cross-section  it  presents  numerous  concentric  striae.  This  inner  zone 
is  slightly  affected  by  acid  stains. 

2.  The  median  zone  is  much  less  thick  than  the  inner,  but  much 
thicker  than  the  external  zone.  This  zone  or  layer  forms  the  thick- 
enings which  project  exteriorly  in  the  form  of  longitudinal  ridges  on 
the  surface  of  the  integument.  It  follows  that  it  is  much  thinner 
at  the  level  of  the  intercostal  furrows  than  at  the  level  of  the  ridges. 
It  appears  not  to  be  lamellar  in  structure,  but  rather  to  present  at 
the  level  of  the  ridges  vertical  striae.  Finally,  its  most  remarkable 
property  is  its  great  affinity  for  basic  stains. 

3.  The  external  zone  is  extremely  thin;  unless  high  magnifications 
are  employed  to  observe  it,  it  easily  escapes  detection.  It  covers  the 
median  zone  in  the  intercostal  furrows  as  well  as  on  the  ridges,  and 
is  not  thicker  at  their  level.  It  is  not  affected  by  either  basic  or  acid 
stains.  This  layer  forms  the  hairs.  Neither  the  median  nor  the 
internal  zone  takes  part  in  the  formation  of  hairs. 

It  follows  from  the  difference  in  affinity  with  regard  to  stains, 
shown  by  the  two  first  layers,  and  the  inability  to  stain  the  outer 
layers,  that  the  three  chitinous  layers  are  easily  distinguished  by  a 
combined  staining  method.  By  means  of  magenta  red  and  picric 
indigo  carmine,  for  instance,  the  inner  zone  becomes  greenish  and  the 
median  zone  dark  red,  while  the  external  layer  remains  colorless. 
Similarly,  by  a combination  of  hematoxylin  and  light  green,  the  inner 
layer  stains  green  and  the  median  layer  deep  black,  the  external 
layer  always  remaining  colorless. 

The  descriptions  of  the  chitinous  integuments  of  insects  do  not 
completely  harmonize  with  those  given  by  Lecaillon  of  Tabanus 
quatuornotatus.  Lecaillon  assumes  two  reasons  for  this  fact:  first, 


144 


THE  EARLY  STAGES  OF  TABANIDiE 


the  staining  methods  employed  have  undoubtedly  been  insufficient; 
second,  the  different  types  of  insect  may  show  important  differences 
in  the  integument.  If  the  integument  is  not  very  thick,  it  may 
often  be  of  simpler  structure.  But  only  exact  observations  can  de- 
termine this  point.  In  the  meantime,  Lecaillon  points  out  that  the 
structure  of  the  integument  of  this  larva  suggests  strongly  that  de- 
scribed by  Dubosq  in  the  myriapods. 

Lecaillon  describes  also  the  attachment  of  the  muscles  on  the  chit- 
inous  membrane  of  the  larva  of  this  species.  The  muscular  fibers  in- 
serted in  the  integument  do  not  end  at  the  epithelium  but  cross  the 
chitinous  layer,  becoming  attached  at  the  median  zone.  But  the  stri- 
ation  of  their  fibers  disappeared  where  they  reach  the  integument, 
and  the  whole  section  contained  between  the  hypothelium  and  the 
median  chitinous  zone  is  formed  by  non-striated  fibrils  forming  a 
sort  of  a tendon.  All  the  muscles  attached  to  the  integument  present 
this  type  of  insertion.  Lecaillon  points  out  that  the  middle  and 
external  layers  form  the  really  hard  and  resistant  part  of  the  chitin- 
ous membrane  of  the  integument,  as  Dubosq  has  shown  in  the  myria- 
pods. This  aids  in  the  understanding  of  the  mode  of  insertion  of  the 
muscle  fibers  in  the  highly  contractile  larvae  of  tabanids,  in  this 
region  of  greatest  resistance.  About  Graber’s  organ,  in  this  species, 
see  page  35  and  Plate  10,  Figs.  Ill  to  116. 

According  to  Bezzi,  the  Tabanus  larva  in  which  Paoli  studied 
Graber’s  organ,  may  have  belonged  to  this  species  (Paoli).  See 
p.  37  (Special  anatomy  of  tabanid  larvae). 

Tabanus  semisordidus  Walker. — The  egg  masses  of  this  South  Ameri- 
can species  have  been  observed  in  British  Guiana,  by  Bodkin  and 
Cleare,  in  1916,  to  be  deposited  on  the  leaves  of  aquatic  grasses  and 
in  some  instances  on  the  leaves  of  young  rice  plants.  They  are  laid 
in  a little  bundle  consisting  of  twenty  or  more  cigar-shaped,  shining 
black  eggs  adhering  to  one  another  and  to  the  leaf  surface. 

Tabanus  solstitialis  Schiner. — A common  European  species. 
Brauer  (1880)  states  that  the  pupa  is  found  in  the  water,  being  green 
in  color  and  provided  with  large  ear-shaped  anterior  spiracles.  The 
larvae  are  not  mentioned. 


WERNER  MARCHAND 


145 


Tabanus  speciosus  Ricardo. — In  Madras,  India,  but  rather  rare; 
feeding  on  cattle  with  Tabanus  striatus  and  albimedius , and  similar  in 
size  and  appearance  to  the  latter. 

According  to  Patton  and  Cragg,  this  species  lays  its  eggs  always 
on  the  leaves  of  water-lilies  growing  in  deep  water.  The  number  of 
eggs  laid  is  between  500  and  600.  The  process  of  oviposition  is  said 
to  be  similar  to  that  of  Tabanus  albimedius , but  Tabanus  speciosus , in- 
stead of  forming  a V-shaped  mass  as  is  usually  the  case  with  the 
larger  tabanids,  lays  its  eggs  in  a round  heap,  which  it  then  plasters 
over  with  a chalk-like  substance,  almost  completely  covering  the 
eggs.  The  egg  mass  is  figured  (Plate  1,  Fig.  19). 

The  larvae  of  the  larger  Indian  tabanids,  including  this  species,  are 
powerful  swimmers  and  have  air  sacs  connected  with  their  tracheal 
tubes,  so  that  they  can  float  or  sink  at  will.  A description  of  the 
larva  is  not  given. 

Tabanus  spodopterus  Meigen. — A common  European  species.  Ac- 
cording to  Schiner,  very  common  in  Austria,  at  the  Neusiedler  See. 
Brauer  (1883)  gives  an  illustration  of  the  larva  (Plate  6,  Fig.  87,  a-}), 
which  he  found,  in  the  month  of  May,  under  dry  leaves  on  the 
ground. 

Tabanus  striatus  Fabricius. — The  early  stages  of  this  species  have 
become  known  through  Mitzmain’s  work,  which  is  the  most  thorough 
investigation  into  the  life  history  of  a tabanid  species  which  we  pos- 
sess. We  cannot  enter  here  upon  his  results  in  as  far  as  the  habits 
of  the  adult  fly  and  its  part  in  the  transmission  of  disease  is  con- 
cerned, but  have  to  limit  ourselves  to  report  on  the  results  obtained 
on  the  early  stages  of  this  species. 

The  eggs  of  Tabanus  striatus  (Plate  2,  Figs.  22  to  27)  were  not  found 
in  the  field,  but  Mitzmain  was  able  to  obtain  them  from  females 
ovipositing  in  captivity.  A large  case  was  built  for  this  purpose 
provided  with  a tank  of  water,  growing  plants,  and  two  animals 
(carabaos)  as  a source  of  food  for  the  flies.  In  a short  time  females 
were  observed  feeding  on  the  hosts  and  several  were  found  ovipositing 
in  various  places  about  the  enclosure. 

The  time  selected  for  egg  laying  under  the  conditions  provided  was 
invariably  during  the  early  afternoon,  never  later  than  2 o’clock. 
This  was  observed  in  nearly  fifty  instances. 


146 


THE  EARLY  STAGES  OF  TABANID.E 


The  eggs  were  laid  in  a compact  mass  either  extended  on  a flat 
surface  or  surrounding  various  attached  objects,  usually  of  small 
diameter,  such  as  projecting  splinters  of  wood,  suspended  fibers  of 
jute  sacking,  fine  brass  wire,  a single  animal  hair,  and  coarse  iron 
wire.  Upon  these  materials  the  eggs  were  laid  in  an  ellipsoidal 
form  sometimes  surrounding  the  objects  completely  or  nearly  so. 
On  one  occasion  two  egg  masses  were  found  upon  a small  splinter  of 
wood  which  they  entirely  enveloped.  The  surfaces  of  the  egg  masses 
were  continuous,  so  that  the  double  mass  resembled  a single  large 
one.  When  eggs  were  found  deposited  on  a flat  surface,  on  two  occa- 
sions a leaf  was  the  object  selected.  These  were  leaves  of  an  orna- 
mental plant  which  was  used  for  shade  purposes  in  the  breeding  cage. 
The  plant  grew  close  to  the  cement  water  tank  in  the  breeding  cage. 
In  all  other  instances  the  eggs  were  deposited  upon  woodwork  on  the 
sides  and  ceiling  of  the  cage,  invariably  upon  the  shaded  portions,  as 
the  under  side  of  beams  and  partitions.  In  egg  laying  upon  flat  sur- 
faces there  was  a strikingly  constant  geometric  form.  Usually  the 
form  assumed  was  roughly  a pentagon  with  a biconvex  center. 

At  the  beginning  of  oviposition  (Plate  2,  Fig.  24)  usually  two  eggs 
are  deposited  in  the  position  of  an  inverted  V.  Three  to  four  eggs  are 
then  laid  on  either  side  of  the  apex  of  this  V,  and  then  one  side  and 
then  the  other  is  built  up,  rather  irregularly  at  first,  until  the  sides 
of  the  pentagon  are  completed.  The  eggs  are  laid  cleanly  and  defi- 
nitely, each  line  slightly  overlapping  the  preceding  one.  When  the 
eggs  are  laid  in  the  extended  order,  they  are  deposited  three  or  four 
layers  in  depth,  but  usually  as  many  as  six  layers  are  required  to 
complete  the  mass  when  the  eggs  surround  a convex  object. 

In  the  process  of  laying,  “ the  body  is  held  away  from  the  egg  mass, 
the  legs  being  planted  firmly.”  When  the  eggs  are  attached  to  one 
of  the  objects  mentioned  above,  the  insect  stands  with  head  down- 
wards, the  fore  legs  suspended  alongside  the  head,  the  hind  and  middle 
legs  supporting  the  weight  of  the  body.  At  the  first  movement,  the 
anal  end  of  the  body  is  bent  towards  the  thorax  under  the  abdomen, 
and  with  a slight  jerk  the  egg  is  laid,  while  the  brush-like  appendage 
of  the  ovipositor  exudes  a tiny  drop  of  liquid  coating  the  egg  as  it  is 
deposited.  The  movement  of  deposition  is  very  much  like  squeezing 
a bit  of  pasty  material  from  a collapsible  metal  tube. 


WERNER  MARCHAND 


147 


In  several  counts  that  were  made  by  Mitzmain,  the  fly  was  observed 
to  lay  with  clock-like  precision  at  the  rate  of  ten  eggs  per  minute. 
This  did  not  vary  whether  the  attached  object  was  above  or  below 
the  fly.  In  three  instances  observed,  the  process  occupied  from  forty 
to  forty-five  minutes.  Both  the  beginning  and  completion  of  the 
egg-laying  process  were  without  deliberation,  the  insect  walking 
away  from  the  mass  of  eggs  and  flying  off  as  soon  as  the  last  egg  was 
deposited. 

When  disturbed  during  oviposition,  the  insect  does  not  fly  and 
can  readily  be  carried  without  attempting  to  escape.  While  in  the 
act  of  laying,  if  interrupted  and  dislodged  from  the  position,  it  imme- 
diately begins  to  deposit  a new  egg  mass.  This  was  twice  repeated 
with  one  female,  and  three  distinct  egg  masses  were  deposited,  all 
identical  in  geometrical  arrangement. 

The  eggs  of  this  species  of  Tabanus  are  laid  with  very  little  cement- 
ing material.  The  cement  used  is  a transparent  substance  “and  not 
dark  and  opaque  as  found  to  exist  in  the  species  described  by  Hine” 
(: Tabanus  lasiophthalmus) . The  cement  provided  by  this  species 
was  tested  and  found  to  be  water-proof,  as  well  as  insoluble  in  various 
grades  of  alcohol  and  xylene. 

The  eggs  (Plate  2,  Fig.  25)  when  laid  are  a pale  clay-yellow,  but 
within  twenty-four  hours  become  slightly  darkened  with  an  ashy 
gray  tinge.  Microscopically  fine  black  striations  can  be  seen  running 
lengthwise  for  nearly  0.5  mm.  from  the  end  opposite  the  micropyle. 

The  shape  of  the  individual  egg  is  that  of  the  muscid  type  with 
more  sharply  pointed  ends;  it  is  not  quite  spindle-shaped.  Several 
eggs  were  measured  and  found  to  average  in  size  1.6  by  0.4  mm. 
The  size  of  the  mass  varies  from  9 to  12  mm.  in  length  by  6 to  9 
mm.  in  breadth. 

The  number  of  eggs  laid  in  a mass  varied  greatly.  In  four  masses 
counted  there  were  respectively  270,  340,  417,  and  425.  Ten  masses 
dissected  from  the  bodies  of  killed  flies  were  found  to  average  405; 
the  greatest  number  found  in  any  female  was  495. 

Mitzman  gives  a detailed  description  of  the  hatching  process. 
Two  egg  masses  were  observed  microscopically  during  the  entire 
process  of  hatching,  and  fourteen  egg  masses  were  noted  as  to  the 
length  of  the  incubation  period.  The  minimum  period  observed 


148 


THE  EARLY  STAGES  OF  TABANID^E 


was  three  days  and  the  maximum  five  days.  Four  days  is  probably 
the  average  length  of  time  required  for  incubation.  It  was  ob- 
served that  the  degree  of  temperature  and  moisture  influenced  the 
time  of  hatching.  Slight  changes  in  either  of  these  factors  can  be 
used  to  control  the  time  of  emergence  from  the  egg.  Mitzmain’s 
observations  on  the  hatching  of  an  egg  mass  are  the  following: 

“Twenty- two  hours  previous  to  the  hatching  of  the  embryo,  certain  unmistak- 
able activities  were  discernible  in  the  egg.  The  first  signs  of  these  were  seen  in 
the  two  eggs  which  formed  the  nucleus  for  the  egg  mass  and  which  are  the  first 
eggs  laid.  These  movements,  as  indicated  by  either  of  the  dark  eye  spots,  could 
be  seen  with  a hand  lens  at  intervals  of  a few  seconds;  their  action  was  similar 
so  that  of  the  bubble  in  a spirit  level.  In  about  an  hour  the  movement  was 
teen  to  be  rather  general  in  the  egg  mass,  accompanied  in  the  eggs  first  laid  by 
an  alternate  collapsing  and  distending  of  the  exochorion.  This  action  is  the 
result  of  the  torpedo-like  movement  of  the  head  capsule  of  the  embryo  in  the  di- 
rection of  the  micropyle  of  the  egg.  The  movement  is  effected  by  the  piston-like 
action  of  the  apophyses  of  the  cephalopharynx,  which  appear  to  work  alternately, 
bringing  the  saw-toothed  mandibles  in  contact  with  the  micropyle  canal.  These 
movements  proceeded  uninterruptedly  during  the  hours  of  the  night,  the  only 
change  observable  being  that  the  body  segments  of  the  embryonic  larva  became 
better  defined.  At  4.25  the  next  morning  the  segments  of  the  embryo  could 
easily  be  counted  through  the  chorion.  The  dorsal  surface  of  the  exochorion 
was  seen  to  be  slightly  shrivelled.” 

“Fully  one  hour  and  thirty  minutes  intervened  during  which  there  was  no 
action  worth  noting.  This  quiescence  was  interrupted  by  a sudden  remarkable 
activity  of  all  of  the  visible  eggs  of  the  mass.  At  6.08  there  was  a general  up- 
heaval of  the  surface  of  the  egg  mass,  an  agitation  within  the  eggs,  and  an  alter- 
nate collapsing  and  distending  of  the  eggshells.  At  6.10  the  first  layer  of  eggs 
gave  birth  to  a silvery  horde  of  young  larvae,  which  at  6.12  had  crawled  from 
view  [Plate  2,  Fig.  27].  Then  ensued  another  spasmodic  agitation  giving  birth 
to  another  lot  of  larvae,  which  crawled  from  the  mass  of  empty  eggshells  [Plate  2, 
Fig.  26].  The  emergence  which  is  effected  by  the  head  structures  is  aided  by  the 
posterior  protuberances,  which  functioning  as  prolegs  push  the  body  of  the  larva 
clear  of  the  eggshells.” 

Mitzmain’s  discussion  of  the  egg  stage  and  of  the  hatching  process 
is  followed  by  a description  of  the  morphology  and  habits  of  the 
young  larvae. 

Immediately  after  emerging  from  the  egg,  the  young  larvae  (Plate 
5,  Fig.  80,  a , b ) seek  concealment.  In  nature,  no  doubt,  resort  would 
be  had  to  the  convenient  water  course  where  aquatic  plants,  drift- 


WERNER  MARCHAND 


149 


wood,  and  stones  would  be  the  probable  hiding  places.  The  larvae 
under  observation  became  very  active  and  crawled  out  of  the  slender 
dish,  a height  of  9 cm.,  and  fell  into  the  water  of  the  basin  pro- 
vided. When  collected  and  placed  in  a deep  glass  vessel  with  some 
water,  the  entire  mass  took  refuge  behind  the  filter  paper  in  the  glass. 
There  they  crowded  side  by  side  with  their  syphons  projecting  from 
the  upper  edge  of  the  paper.  When  disturbed  and  forced  to  take  to 
the  water,  they  were  found  in  thirty  minutes  reassembled  in  the  char- 
acteristic gregarious  fashion  behind  the  filter  paper  against  the 
glass. 

For  convenience  in  study,  a majority  of  the  larvae  were  transferred 
when  1 day  old  to  individual  glass  jars  one-third  filled  with  clean  wet 
sand  from  the  lake  shore  and  provided  with  strips  of  filter  paper 
soaked  in  muck  from  the  creek  bottom.  The  jars,  which  were  the 
common  half  pint  jelly  glasses  recommended  by  Hine,  were  kept 
covered  with  filter  paper,  held  in  place  by  the  tin  lid  which  had  a disk 
cut  from  its  top  to  admit  air.  By  renewing  the  moisture  on  the 
strip  of  filter  paper  in  the  jars,  the  filter  paper  cover  serves  ideally 
to  control  the  humidity. 

A considerable  number  of  the  larvae  were  not  separated,  but  were  left 
together  for  observation  in  a glass  dish  with  a few  strips  of  paper 
saturated  with  muck  from  the  creek.  The  young  larva  is  briefly 
described  as  follows: 

“The  larva  one  hour  after  hatching  [Plate  5,  Fig.  80,  a , b]  is  1.5  mm.  in  length. 
The  following  day  several  were  found  to  measure  1.8  mm.  The  general  color 
is  a dirty  white  with  a tracheal  system  of  waxy  white,  the  abdominal  contents 
pale  green,  and  the  Malpighian  tubules  of  a lilac  color.  There  are  2 black 
eye-spots  located  midway  on  the  head  capsule.  The  latter  tapers  to  a sharp- 
pointed  mouth  with  a prominent  pair  of  great  hooks  or  mandibles.  The  seg- 
ments are  provided  with  typical,  conical,  truncated,  prolegs,  each  armed  with  a 
chaplet  of  medium  long,  brown  hairs.  The  siphon  which  is  carrot-shaped  at 
this  stage  is  a prominent  feature.” 

Food  in  a variety  of  forms  was  furnished  the  larvae.  They  thrived 
from  the  start  on  minute  crustaceans,  larvae  of  Stomoxys,  mosquito 
larvae,  and  young  angleworms.  Full  grown  angleworms  were  found 
unsuitable,  and  larvae  of  the  blow-fly  and  flesh-fly  were  not  satisfac- 
tory unless  killed  previously,  as  they  were  capable  of  killing  or  in- 


150 


THE  EARLY  STAGES  OF  TABANID^E 


juring  even  well  developed  Tabanus  larvae.  As  soon  as  the  insect 
becomes  aware  of  the  presence  of  food,  the  claw-like  mandibles  are 
protruded  from  the  head  capsule,  and  bury  themselves  in  the  live 
food  like  meat  hooks.  With  a slight  curve  dorsally,  the  larva’s  body 
is  brought  forward,  and  a small  portion  of  the  food  is  lacerated.  This 
is  aided  by  a twisting  of  the  head  and  a pulling  with  the  extended 
jaws.  The  mandibles  are  brought  together  with  a rapid  clawing 
action,  the  parts  working  in  apposition.  When  prehension  is  effected, 
the  jaws  move  alternately  upwards  and  downwards  and  laterally, 
and  the  bolus  is  swallowed  in  fibrous  strands. 

Seeking  and  devouring  food  is  not  a continuous  operation  as  it  is 
in  the  case  with  Stomoxys  and  the  dung-flies.  The  Tabanus  larva 
requires  a long  rest  after  a sufficient  meal  is  taken.  A 2 day  old 
Tabanus  is  capable  of  devouring  two  half  grown  larvae  of  Stomoxys 
in  twenty-five  minutes.  In  one  instance  a full  grown  Stomoxys  larva 
was  destroyed  in  exactly  twenty  minutes.  Here  the  attack  on  the 
Stomoxys  was  made  through  accidental  collision,  the  Tabanus  in- 
stinctively thrusting  out  its  mouth  and  tentatively  taking  a bite. 
It  apparently  became  greatly  excited  (this  was  its  first  meal),  and 
thrusting  its  head  into  the  body  of  the  Stomoxys  larva,  commenced 
to  probe  by  twisting  its  head  rapidly.  In  less  than  a minute  the 
cuticle  was  broken  through  and  an  ample  slit  was  made  through 
which  the  entire  head  was  buried  in  the  body  of  the  victim,  where- 
upon an  energetic  gouging  took  place.  The  Tabanus  worked  through 
the  cephalic  third  of  the  body  upwards  to  the  head,  then  worked  in 
the  other  direction  on  the  lower  two-thirds.  This  gouging  was  con- 
tinued until  the  Stomoxys  had  become  completely  eviscerated,  during 
which  time  the  head  of  the  Tabanus  kept  steadily  probing,  twisting 
its  pharynx  from  side  to  side,  and  pushing  forward  with  its  rostrum 
until  the  Stomoxys  larva  was  completely  devoured  with  the  exception 
of  the  cuticle. 

The  full  grown  Tabanus  larva  does  not  wait  for  its  food,  as  is  the 
tendency  in  the  young  stage,  but  actively  pursues  its  prey.  When 
an  angleworm  is  seen,  perhaps  2 mm.  distant,  the  elastic  head  cap- 
sule of  the  larva  darts  forth,  curves  its  claw-like  hooks  about  the 
worm’s  body,  and  with  its  head  curled  under  its  struggling  prey,  re- 
treats quickly  into  the  sand  until  all  but  its  cephalic  end  is  hidden. 


WERNER  MARCHAND 


151 


It  begins  to  feed  then,  devouring  in  twenty  minutes  an  angleworm 
fully  four  times  its  own  length. 

The  intestinal  tract  seen  through  the  hyaline  cuticle  soon  par- 
takes of  the  color  of  the  food  ingested.  The  color  is  pale  brown  when 
the  food  consists  of  the  wet  muck  in  which  crustaceans  and  minute 
forms  are  sought.  As  a result  of  feeding  on  blow-fly  larvae  and  angle- 
worms,  the  young  Tabanus  assumes  a variegated  color.  The  intes- 
tinal tract  then  appears  tinted  with  green,  yellow,  brown,  and  red 
particles  of  the  food. 

In  one  set  of  larvae,  as  Mitzmain  says,  “The  origin  of  cannibalism 
as  an  acquired  habit  was  observed .”  This  was  seen  in  larvae  which 
had  been  kept  together  for  four  days  since  their  birth.  Until  that 
day  no  food  was  offered  them  except  that  which  they  might  have 
obtained  from  the  surrounding  creek  water.  Apparently  they  lived 
together  amicably  with  their  bodies  compressed  against  the  glass 
dish  and  the  bit  of  filter  paper.  A live  angleworm  was  placed  in  the 
glass  dish  while  the  resting  larvae  were  observed  with  a lens.  The 
worm  was  not  placed  in  the  immediate  vicinity  of  the  mass  of  larvae, 
but  nearly  4 cm.  distant.  The  presence  of  the  food  appeared  to  act 
as  a stimulus.  No  movement  was  made  towards  the  worm,  but  each 
larva  appeared  to  become  greatly  excited  and  began  to  prod  the 
larva  nearest  to  it  and  to  nip  its  neighbor's  appendages;  several 
instances  of  laceration  were  noted.  This  doubtlessly  marked  the 
beginning  of  systematic  cannibalism.  From  this  cause,  39  of  the 
365  larvae  kept  in  the  large  glass  dish  were  destroyed  within  four 
days.  Four  dead  bodies  were  recovered.  Upon  another  occasion 
the  extent  of  cannibalism  was  much  more  marked.  A lot  of  415 
larvae  which  hatched  on  November  12,  1912,  was  placed  in  a deep 
glass  dish  with  moist  lake-beach  sand,  and  fed  daily  on  angleworms. 
Each  morning  it  was  observed  that  only  about  one-half  of  the  worms 
supplied  the  previous  day  were  eaten,  so  that  with  the  daily  fresh 
supply  more  than  enough  food  was  present.  Another  lot  of  300 
larvae,  the  same  age  as  the  preceding,  was  kept  in  individual  glasses 
under  similar  conditions.  On  December  6,  counts  were  made  of  the 
survivors  in  the  large  glass  dish.  Thirty-five  larvae  remained,  of 
which  eighteen  were  the  maximum  size,  eleven  were  a little  more  than 
one-half  this  size  but  equal  to  the  largest  found  in  the  individual 


152 


THE  EARLY  STAGES  OF  TABANIDiE 


jars,  and  the  remaining  six  larvae  were  so  small  as  to  be  easily  over- 
looked. The  count  of  the  larvae  from  the  individual  jars  showed  a 
loss  of  twelve,  or  less  than  5 per  cent.  Allowing  5 per  cent  for  loss 
from  other  causes,  it  appeared  that  above  85  per  cent  of  the  larvae 
kept  together  in  the  large  jar  was  destroyed  through  cannibalism. 

It  has  been  observed  by  Hine  in  other  species  that  a Tabanus  larva 
is  enabled  to  survive  for  a few  days  in  the  absence  of  food.  In  this 
species,  likewise,  there  seems  to  be  a decided  resistance  to  starvation, 
two  instances  showing  periods  of  ten  and  twelve  days. 

Mitzmain  found  the  movements  of  the  body  to  be  in  general  similar 
to  those  of  larvae  of  the  muscid  type.  There  is  a general  progressive 
peristaltic  movement,  invariably  accompanied  by  a decided  telescop- 
ing of  the  segments.  The  head  is  raised  as  the  prolegs  of  the  anal 
end  push  the  body  forward,  then  it  is  lowered.  The  mouth  is  pro- 
jected when  the  head  capsule  is  extended,  but  recedes  quickly  when  the 
glass  sides  of  the  container  or  any  obstacle  is  encountered.  The  larva 
can  easily  move  backwards  for  a considerable  distance.  This  it  does 
if  wedged  in  a tight  place  or  in  capturing  food  when  it  retreats  into  a 
channel  previously  made  in  the  sand. 

The  larvae  readily  adapt  themselves  to  a watery  medium.  They 
can  remain  submerged  for  several  minutes  at  a time  without  apparent 
discomfort.  When  placed  in  deep  water  the  movements  of  the 
body  consist  of  a general  struggling  without  apparent  definite  pur- 
pose. At  any  rate,  there  is  little  or  no  progression,  the  body  doubles 
like  a bow,  the  head  and  tail  meeting,  then  straightens  with  a whip- 
ping action.  In  swimming,  the  body  is  held  along  the  surface  of  the 
water  and  the  syphon  is  extended  towards  the  air  in  a manner  sug- 
gestive of  the  larva  of  an  anopheline  mosquito.  The  principal  move- 
ment observed  is  that  of  simple  telescoping  of  one  segment  into  an- 
other. When  speed  is  required  or  an  obstruction  is  to  be  passed, 
there  is  a vigorous  whipping  movement  of  the  syphon  laterally, 
towards  and  away  from  the  head.  This  latter  movement  is  also 
noted  when  the  insect  is  disturbed. 

When  a young  larva  is  placed  in  water  containing  entomostracans 
or  other  minute  animals,  a barely  perceptible  churning  of  the  liquid 
occurs  in  the  region  of  the  mouth.  This  disturbance  is  no  doubt 
caused  by  the  movements  of  minute  tentacles  which  assist  in  procur- 


WERNER  MARCHAND 


153 


ing  food.  These  tentacles  form  the  armature  of  the  stomal  disk, 
consisting  of  a process  arranged  like  a turnstile  mounted  on  a pitted 
chitinous  plate  at  the  base  of  the  great  hook  or  mandible.  In  the 
very  young  larva  the  stomal  disk  appears  as  a chaplet  of  delicate 
chitinous  rods.  When  a larva  is  treated  with  strong  caustic  potash, 
the  stomal  disk  appears  to  be  the  only  structure  which  resists  its  ac- 
tion, the  other  chitinous  structures,  even  the  heavy  pharyngeal 
apophyses,  are  bleached.  In  common  with  the  other  chitinous 
portions  of  the  head  capsule  the  stomal  disk  is  shed  at  each  of  the 
three  ecdyses. 

An  account  of  the  general  development  of  the  larva  follows: 

The  young  larva  shows  in  its  form  and  behavior  its  adaptability 
to  an  aquatic  life.  This  is  well  illustrated  when  a larva  is  placed  in 
an  aquarium  containing  mosquito  wrigglers.  The  Tabanus  has  no 
difficulty  in  keeping  afloat  with  them  and  foraging  at  will  upon  the 
active  culicid  larvae.  Tabanus  larvae  have  been  observed  capturing 
wrigglers,  holding  them  by  their  jaws  under  the  water,  and  actually 
killing  the  culicid  through  drowning.  In  one  instance  a Tabanus 
larva  held  its  victim,  which  was  fully  five  times  its  size,  suspended 
beneath  it  in  such  manner  that  the  culicid  was  unable  to  project  its 
syphon  for  breathing  purposes,  while  that  of  the  Tabanus  was  func- 
tional. The  Tabanus , obtaining  a secure  perch  by  dragging  itself 
and  the  prey  above  the  water,  devoured  the  mosquito  wriggler  in  a 
few  minutes.  In  another  instance  the  weight  of  the  culicid  pulled 
its  captor  under  the  water  to  the  sandy  bottom  a distance  of  nearly 
30  cm.  Here  the  Tabanus  showed  its  superior  vitality  by  remaining 
attached  for  nearly  two  minutes  until  apparently  assured  of  the 
immobility  of  its  prey,  then,  releasing  its  hold,  the  Tabanus  larva 
struggled  to  the  surface  where  it  rested  with  syphon  extended.  The 
mosquito  larva  meanwhile  moved  feebly  several  times,  and  suc- 
cumbed within  a few  minutes. 

This  adaptability  is  lost,  however,  in  the  developed  larva  which 
becomes  more  slothful  in  movement  and  grub-like  in  superficial  ap- 
pearance. Both  extremities,  the  head  and  the  syphon,  become  ob- 
tuse in  form,  and  the  ventral  protuberances  functioning  as  prolegs 
become  more  truncated.  Growth  after  the  second  molt  becomes 
noticeably  less  in  length  and  more  in  thickness.  The  greatest  growth 


154 


THE  EARLY  STAGES  OF  TABANIDAE 


observable  was  shown  to  be  between  the  periods  of  the  first  and  the 
second  molts. 

The  following  table  is  given  by  Mitzmain  to  show  the  normal  growth 
of  a larva.  The  measurements  and  the  critical  stages  of  life  are 
indicated. 

TABLE  i. 

Progress  of  Development  of  a Larva. 


Date. 

Length. 

Stage  of  development. 

mm. 

Sept 

. 15 

1.5 

At  birth. 

a 

16 

1.8 

1 day  old. 

a 

20 

3.0 

a 

21 

4.0 

it 

22 

5.0 

tt 

23 

6.5 

a 

26 

11.0 

After  first  molt. 

it 

30 

20.0 

Oct. 

8 

22.0 

u 

9 

25.0 

Second  molt. 

a 

12 

27.5 

a 

17 

29.5 

Mature  larva. 

“ 

21 

27.5 

it 

24 

17.5 

Pupa,  third  molt. 

In  all  biological  accounts  of  the  Tabanidae  there  appears  to  be  one 
phenomenon  which  is  uniformly  noted.  This  is  the  remarkable  dif- 
ference in  growth  shown  by  individual  flies  of  the  same  species.  The 
only  process  in  the  development  which  seems  to  be  synchronous  is 
the  hatching  of  the  eggs.  After  that  the  variations  in  time  of  develop- 
ment are  extreme.  In  Tabanus  striatus , for  example,  some  larvae 
twelve  days  old  measured  3 mm.,  while  others  under  precisely  the 
same  conditions  measured  fully  11  mm.  In  another  instance  two 
flies  emerged  as  well  developed  imagos  October  31,  while  twenty- 
seven  of  the  same  brood  still  remained  apparently  healthy  in  the 
larval  stage  December  20. 

Mitzmain  is  the  first  to  mention  molting  or  ecdysis  in  tabanids, 
stating  that  he  has  been  unable  to  find,  “in  the  very  meager  litera- 
ture available,”  any  reference  to  the  molting  process  in  Tabanidae. 
It  is  referred  to  indirectly  by  King  at  Khartoum,  who  found  in 


WERNER  MARCHAND 


155 


Tabanus  biguttatus  the  shed  larval  skin  adhering  to  the  “puparium.”26 
Mitzmain  had,  however,  not  seen  Paoli’s  work  on  the  organ  of 
Graber,  in  which  also  mention  is  made  of  mol  tings. 

By  Mitzmain  the  process  of  shedding  the  skin  was  observed  in 
Tabanus  striatus  in  a great  many  instances.  The  time  of  molting 
of  a brood  of  larvae  is  extremely  variable,  which  is  consistent  with  the 
great  variations  noted  in  the  time  of  development  in  general.  The 
process  has  been  accurately  noted  in  two  individual  larvae,  although 
observed  superficially  in  numerous  others.  The  three  molts  are  simi- 
lar in  their  general  aspects,  the  main  distinction  being  the  more 
profound  changes  produced  in  the  insect  at  the  later  molts. 

The  usual  preparations  for  molting  were  observed  in  this  species. 
The  premonitory  signs  were  the  refusal  of  food,  uneasiness  when 
exposed  to  light,  desire  to  find  a remote  corner,  and  finally  the  stiff- 
ening of  the  cuticle.  In  one  instance  the  larva  was  found  in  one 
spot  pressed  against  the  glass  for  three  days.  Here,  between  the 
sand  and  the  glass  of  the  jar,  an  excrementous  cement  was  used  to 
fasten  the  end  of  the  abdomen.  This  material  holds  the  end  of  the 
body  very  securely,  although  the  remainder  of  the  body  requires  free 
lateral  movement.  By  the  time  the  ecdysis  is  completed,  the  head 
has  moved  3 mm.  from  the  spot  where  preparations  for  the  process 
were  made,  while  the  anal  end  has  retained  its  original  position. 

The  shedding  of  the  skin  usually  requires  several  hours;  in  one  in- 
stance, due  no  doubt  to  interference  by  the  observer,  the  time  was 
nearly  twenty-four  hours.  In  the  first  and  second  molts,  splitting 
of  the  cuticle  begins  at  the  thorax,  resulting  in  the  tearing  out  of  the 
entire  head  capsule  which  adheres  to  the  molt  during  the  remainder 
of  the  process.  The  anal  segments  are  molted  finally  and  the  larva, 
emerging  in  its  new  skin,  crawls  its  length  on  the  cast  skin  and  rests 
alongside  it  for  two  or  more  hours. 

The  first  molt  begins  with  larvas  7 days  old,  the  majority  molting 
before  the  tenth  day.  The  second  molt  usually  occurs  after  an  in- 
terval of  at  least  four  days,  and  in  some  larvae  as  late  as  eight  days, 

26  The  use  of  the  term  11  puparium”  for  the  tabanid  pupa  should  not  be  en- 
couraged. The  tabanid  pupa  is  a true  pupa,  in  contrast  with  that  of  muscids, 
or  syrphids,  where  the  true  pupa  is  enclosed  in  the  last  larval  skin,  justifying 
the  name  puparium  to  differentiate  it  from  a free  pupa. 


156 


THE  EARLY  STAGES  OF  TABANID^E 


when  fifteen  to  eighteen  days  old.  The  time  of  the  third  molt  pre- 
cedes immediately  the  appearance  of  the  puparium.  This  period,  as 
has  been  noted,  shows  the  greatest  diversity  among  individuals  of  the 
brood.  The  third  molt  in  twelve  instances  was  shed  between  the 
ninth  and  twelfth  days  of  life. 

In  other  individuals  the  process  was  not  completed  within  three 
months,  yet  the  adult  fly  was  an  apparently  healthy  insect. 

Certain  unimportant  changes  in  morphology,  dependent  on  the 
molting  process,  are  noticeable.  The  loss  in  size  due  to  contraction 
of  the  cuticle  preparatory  to  ecdysis  is  usually  compensated  by  a 
substantia  extension  immediately  following  the  process.  The  extent 
of  shriveling  of  the  cuticle  is  represented  by  1 mm.  in  the  first  molt- 
ing, 1.5  to  2 mm.  in  the  second  stage,  and  2 to  3 mm.  preparatory  to 
the  third  stage.  There  is  a notable  increase  in  length  resulting  from 
the  second  ecdysis.  A larva,  measuring  22  mm.  on  the  day  previous 
to  the  shedding  of  the  skin,  measured  fully  25  mm.  the  following 
day.  In  measurements  of  this  sort  one  must  make  allowance  for  the 
extraordinary  amount  of  telescoping  of  segments.  As  much  as  5 
mm.  may  be  involved  in  this  process. 

The  structures  mainly  involved  in  the  ecdysis  are  the  tracheal  sys- 
tem and  the  appendages  of  the  head.  The  anal  ring  of  the  trachea 
constituting  the  syphon  is  drawn  off  in  each  molt  in  a perfectly 
cylindric  form.  The  body  trachea  is  torn  from  its  connections  in 
irregular  strands.  The  entire  head  capsule,  including  the  chitinous 
pharyngeal  framework,  the  great  hook,  and  other  mouth  structures, 
are  found  in  perfect  form  in  the  various  exuviae.  These  parts  upon 
renewal  in  the  larVa  become  more  heavily  reinforced. 

The  exuvia  (Plate  5,  Fig.  81,  a , b,  c)  is  usually  in  a good  state  of 
preservation;  crumpled,  to  be  sure,  but  it  can  be  extended  in  alcohol 
to  three-fourths  the  length  of  the  larva.  Following  each  ecdysis, 
the  larva  is  invariably  leaden  gray  with  tracheal  strands  of  waxy 
white.  Three  anal  segments  including  the  syphon  become  lead- 
colored  and  stiffened  in  structure.  They  are  at  this  stage  more  trun- 
cated, with  an  anal  band  of  cuticle  1 mm.  in  depth,  making  the 
syphon  appear  somewhat  atrophied.  This  is  no  doubt  consistent 
with  its  restricted  function.  The  color  of  the  viscera  has  changed 
from  the  brilliant  red  and  yellow  to  an  indeterminate  white,  and  the 


WERNER  MARCHAND 


157 


lilac  tint  of  the  Malpighian  tubules  has  changed  to  a salmon  color. 
The  latter  changes  are  due  probably  to  a clearing  process,  in  which 
the  larva  indulges  during  the  quiescent  stage  preceding  each  ecdysis. 

After  the  second  molt  the  fleshy  protuberances  functioning  as  pro- 
legs become  reinforced  with  a slight  cuticular  ring  at  their  bases. 
The  mouth-parts  at  this  stage  are  heavily  chitinized.  The  great 
hooks  or  mandibles  show  a marked  serration  of  the  biting  edge.  The 
head  projects  more,  exposing  the  dark  brown  ocelli,  which,  prior  to 
the  second  molt  are  seen  only  through  the  cuticle  of  the  thorax  situ- 
ated nearly  on  the  middle  of  the  concealed  head  capsule. 

The  signs  characteristic  of  the  final  molt  which  results  in  pupation 
are  refusal  of  food,  restlessness,  attempted  migration,  and  finally 
burial  in  the  sand  at  the  bottom  of  the  jar.  The  body  decreases 
slightly  in  length,  but  the  thickness  remains  the  same. 

On  the  extremity  of  the  abdomen,  tiny  tubercles  appear  which 
project  more  from  time  to  time,  becoming  tapering  and  spike-like. 
Near  the  caudal  end  of  the  abdominal  segments,  roots  of  hairs  ap- 
pear. These  at  first  resemble  brown  spots  of  pigment  and  gradually 
lengthen  into  stiff  brown  hairs.  The  cuticle  on  the  body  becomes 
stiffened  and  shingle-like  at  the  joints  of  the  segments.  The  latter 
telescope  less,  and  one  can  see  numerous  particles  of  sand  embedded 
in  the  joints  of  the  segments.  These  sand  particles  have  been  car- 
ried in  during  the  telescopic  movements  of  the  abdomen. 

After  the  fully  developed  larva  passes  through  a period  of  semi- 
dormancy buried  in  the  sand,  the  skin  is  seen  to  be  ridged  with  cutic- 
ular plates.  The  head  region  is  reinforced  by  stiffened  cuticle,  and 
the  mouth  orifice  is  closed  by  a plug  of  hard  rose-colored  cuticle. 
This  pigmented  material  lines  the  entire  pharyngeal  sinus,  plugging 
the  mouth  and  the  cephalopharynx.  The  cuticular  plug  has  a sub- 
stantial fold  which  forms  a slit  for  the  passage  of  the  molting  mouth. 
Caudally  a similar  impervious  mass  closes  the  opening  of  the  syphon. 
A cuticular  collar  strengthens  the  base,  and  the  connective  tissue 
surrounding  the  trachea  of  the  tract  of  the  syphon  tends  to  contract. 
Then  the  supports  of  the  central  trachea  are  gradually  cast  loose  by 
a gentle  wriggling  of  the  insect’s  body.  About  this  time  there  is  a 
general  wrinkling  of  the  epidermis,  the  folds  telescoping  upon 
each  other,  and  the  surface  becomes  like  parchment. 


158 


THE  EARLY  STAGES  OF  TABANLDiE 


Synchronous  with  the  primary  contraction  of  the  segments,  a light 
pea-green  suffuses  the  last  three  segments  of  the  body.  The  re- 
mainder of  the  larva  changes  to  this  color  over  night.  By  morning 
the  abdominal  segments  have  changed  from  green  to  ocher,  when 
the  molting  of  the  cuticle  ensues.  The  shedding  takes  place  in  sec- 
tions. The  chitinous  framework  of  the  head  is  thrown  off  like  a 
hood.  This  portion  is  everted  upon  the  body,  and  remains  dangling 
from  the  exuvia  during  the  process.  One-half  the  length  of  the  skin 
is  loosened  on  the  side  opposite  that  to  which  the  chitinous  framework 
of  the  head  is  attached.  This  is  shed  by  a peculiar  auger-like  move- 
ment of  the  tail  end  which  is  not  attached  to  the  glass  or  other  ob- 
ject in  the  container,  as  in  the  previous  molts.  The  skin  is  virtually 
unrolled  from  the  detached  head  to  the  anal  end,  where  it  lies  in  a 
crumpled  heap.  Then  the  skin  of  the  other  side  of  the  body  begins  to 
be  shed.  The  chitinous  framework  constituting  the  former  head 
capsule  of  the  larva  becomes  rolled  up  in  the  exuvia,  while  the  skin 
is  torn  slowly  from  the  new  membrane.  When  the  first  half  of  the 
skin  is  peeled  off  to  the  anal  tip,  the  cast  skin  becomes  attached  to 
some  object.  In  this  instance  the  glass  of  the  jar  served  as  an  anchor- 
age during  the  remainder  of  the  ecdysis. 

The  upper  half  of  the  body  of  the  newly  molted  larva  is  encased 
as  in  an  armor  in  pouches  and  pads  of  integument,  outlining  in  a 
gauzy  film  the  future  appendages  of  the  fly. 

Mitzmain’s  description  of  the  full  grown  larva  (Plate  5,  Fig.  80, 
c)  is  given  below: 

“The  length  is  28  to  29.5  mm.;  the  width,  3 to  4 mm.  The  anterior  half 
of  the  body  is  a greenish  yellow,  the  remainder  is  a dirty  white.  At  this  stage 
the  form  is  grub-like.” 

“The  head  capsule,  which  occupies  one-fifth  the  length  of  the  larva,  is  a 
cylindrical  bulb,  formed  by  the  invagination  of  the  thoracic  ectoderm.  It  sup- 
ports the  eyes,  the  antennae,  and  the  mouth  parts.  It  is  bound  by  a framework 
of  chitinous  rods,  the  cephalopharyngeal  apophyses.  This  structure,  observed 
through  the  thorax  when  the  insect  is  in  action,  is  composed  of  four  black,  me- 
dium-thick, skeletal  pieces  running  the  length  of  the  three  cephalic  segments  in 
the  form  of  a pyramid,  with  its  apex  provided  with  the  external  mouth  parts. 
It  terminates  in  the  claw-like  mandibles  which  are  similar  in  color  and  texture.” 

“The  mandibles  [Plate  5,  Fig.  79]  are  heavy,  powerful  structures,  slightly  ser- 
rated on  their  inner  surfaces.  The  musculature  of  these  appendages  permits  the 


WERNER  MARCH  AND 


159 


two  elements  working  in  apposition.  At  rest  they  are  held  horizontally,  and  can 
be  projected  suddenly  and  thrust  vertically  downward,  which  is  obviously  of 
great  assistance  in  grasping  the  prey.” 

“The  palpi  and  antennae  in  this  species  are  silvery  white,  and  usually  found 
glistening  with  moisture.” 

“The  eyes  are  oval  in  shape,  with  the  long  axes  parallel.  When  the  larva  is 
prepared  to  molt,  the  pigmented  spots  are  usually  distorted.  In  this  species 
the  eye  spots  or  ocelli  are  very  prominent,  especially  in  the  younger  stages  of 
the  larva.  They  can  be  first  seen  in  the  embryo  where  they  appear  as  dark 
beaded  structures  through  the  chorion  of  the  well  developed  egg.  In  the  young 
stage  of  the  larva  the  eyes  appear  in  the  pharyngeal  cavity  midway  between  the 
mouth  and  the  cephalopharynx,  and  as  growth  continues  they  are  located  nearer 
the  distal  end  of  the  head  capsule;  so  that  when  the  larva  is  full  grown  and  the 
mouth  structures  protrude  in  locomotion  or  prehension  the  eye  spots  are  seen 
to  project  on  the  head  capsule  with  the  mouth  parts.” 

“The  trachea  which  terminates  in  the  conical  tubular  syphon  is  lead  gray  in 
contrast  to  the  dense  white  of  that  portion  anterior  to  the  anal  segment.  Anterior 
to  the  syphon  there  is  a cuticular  cellar  of  slightly  darker  shade.” 

“The  prolegs  are  formed  by  truncated  projections,  six  in  number,  three  on 
each  side  of  the  midventral  line  and  extending  laterally.  Each  protuberance  is 
provided  with  a tuft  of  short,  fine,  brown  hairs.  These  hairs  appear  to  be  sur- 
rounded by  a secretory  substance,  which  is  slimy  in  character.” 

“At  the  base  of  the  syphon,  beneath  the  cuticle  on  the  dorsal  side  opposite 
the  anal  capsule,  is  a tiny  structure  which  attracts  attention  on  account  of  its 
movements  and  peculiar  arrangement.  In  the  newly  hatched  larva  it  is  a process 
composed  of  four  lustrous  black  disks  arranged  in  two  pairs,  one  in  front  of  the 
other,  and  set  in  a mass  of  fat  bodies.  The  larger  of  the  disks,  the  anterior 
pair,  is  less  than  0.1  mm.  in  diameter.  The  movement  of  the  process  is  similar 
to  that  of  a pendulum,  and  is  active  only  when  the  larva  moves.  With  each 
molt  these  disks  become  smaller  and  increase  in  number.  In  the  .full  grown 
larva  the  process  becomes  a triangular  mass  of  loosely  arranged  beaded  disks. 
They  appear  to  be  mere  specks  of  pigment  beneath  the  skin,  but  their  structure 
and  action  are  so  constant  that  either  the  process  is  characteristic  of  the  species 
or  investigators  have  overlooked  or  ignored  them  in  other  species.” 

The  description  of  the  pupa  (Plate  12,  Fig.  152,  a , b ; Fig.  143,  a , 
b)  after  Mitzmain  is  given  below: 

“The  average  length  is  18  mm.,  and  width,  3.5  mm.  The  color  is  pale  brown, 
the  last  2 segments  of  the  abdomen  being  slightly  darker.  The  head  tubercles 
are  not  clearly  defined:  color,  dark  brown.  The  prothoracic  spiracular  tubercle  is 
slightly  elevated,  oblique;  rima,  salmon-colored  and  crescentic  in  form.” 

“The  first  abdominal  spiracle  is  perfectly  round  and  larger  than  the  others, 
which  are  slightly  ovoid;  the  rima  of  all  the  spiracles  curves  from  above 
posteriorly.” 


160 


THE  EARLY  STAGES  OF  TABANED^E 


“The  terminal  abdominal  segment  [Plate  12,  Fig.  143,  a,  £>]  shows  a sexual 
distinction  in  the  arrangement  of  the  short  spines  midway  on  the  ventral  side, 
anterior  to  the  terminal  teeth.  In  the  male  ten  to  twelve  of  these  spines  form 
a continuous  serrated  border.  In  the  female  the  spines  occur  in  two  groups  of 
four  to  six  spines  similar  to  those  of  the  male,  but  separated  by  space  equal  in 
width  to  that  of  one  of  the  groups.” 

“The  terminal  teeth  of  the  posterior  segment  are  arranged  with  two  pairs 
close  together  on  the  dorsal  side  and  one  pair  on  the  ventral  side.  These  teeth 
are  black-tipped  and  acute;  all  of  them  are  directed  slightly  outward.  The 
lateral  teeth  of  the  two  dorsal  pairs  are  the  longest.  The  ventral  pair  is  smaller 
and  is  set  slightly  in  from  the  periphery  of  the  segment.” 

“After  the  final  ecdysis  which  results  in  the  formation  of  the  puparium,  the 
nymph,  at  first  a light  green,  gradually  changes  to  yellow.  Upon  the  second  day, 
the  eye  spots  change  from  yellowish  to  pale  brown,  then  to  a chocolate  color. 
Beginning  with  the  third  day  the  pads  of  the  wings  and  the  legs,  at  first  light 
brown,  assume  the  same  color  as  the  eyes.  The  chitinous  pad  enveloping  the 
wing  is  densely  opaque,  so  that  only  the  plications  of  the  developing  wing  can 
be  discerned.  Upon  the  penultimate  day,  the  fifth  or  sixth  usually,  the  abdomen, 
which  heretofore  has  been  a uniform  yellow-brown,  becomes  striped  with  light 
orange  and  brown,  which  colors  gradually  deepen  until  the  time  of  emergence.” 

The  process  of  emergence  from  the  puparium  is  also  described  by 
Mitzmain  (Plate  12,  Fig.  152,  b): 

“In  emergence,  the  puparium  which  lies  buried  to  some  depth  in  the  sand  is 
invariably  dragged  to  the  surface  where  the  final  acts  of  emergence  are  com- 
pleted. Two  or  three  days  prior  to  the  act  of  emergence,  the  puparium  shows 
considerable  mobility  when  disturbed  by  handling  or  stimulated  by  light.  Cer- 
tain movements,  which  one  learns  through  numerous  observations  to  be  charac- 
teristic, can  be  considered  as  actually  premonitory.  These  occur  usually  from 
ten  to  twenty  minutes  prior  to  the  breaking  of  the  cuticle,  and  serve  the  observer 
as  warning  signs.  If  during  this  interval  a low  power  lens  is  focussed  on  the 
compound  eye,  the  epidermis  of  the  fly  separating  from  its  connective  tissue  fas- 
tening of  the  puparium  can  easily  be  seen.  This  action  resembles  strikingly  a 
wave  of  water  moving  between  the  walls  of  the  puparium  and  the  epidermis  of 
the  fly.  It  may  be  considered  as  the  movements  of  a semiliquid  layer  between  the 
fly  and  its  puparium.  Another  movement,  which  can  be  observed  within  a few 
minutes  after  that  previously  described,  is  the  momentary  contraction  and  ex- 
pansion of  the  sides  of  the  abdomen  between  the  two  lateral  ridges.  This  too,  no 
doubt,  is  effective  in  tearing  the  connective  tissue  lining  to  facilitate  emergence. 
A few  minutes  later  the  anal  end  of  the  abdomen  is  torn  loose  from  its  fastening, 
and  emergence  of  the  fly  begins.” 


WERNER  MARCHAND 


161 


Since  the  puparium  is  unrolled  from  the  head,  the  compound  eyes 
are  soon  exposed  to  view,  so  that  the  sex  of  the  fly  may  be  distinguished. 
The  appendages,  antennae,  palpi,  and  mouth-parts  are  dimly  visible. 
The  head  appendages  are  freed  primarily  by  the  spasmodic  wriggling 
of  the  abdomen,  but  the  labellum,  which  is  seen  to  become  turgid  and 
flaccid  in  turn  by  the  injection  of  air  into,  and  withdrawal  of  air 
from,  the  “ extensive  tracheal  sacs  which  lie  in  the  cavities/7  and  the 
erectile  stomal  disk  through  the  pressure  downwards  against  the  walls 
of  the  puparium,  assist  also  in  the  process.  That  these  head  ap- 
pendages assist  effectually  in  the  emergence  is  evident  from  the 
lines  of  cleavage  in  the  enveloping  membranes. 

The  puparium  splits  on  the  median  line  of  the  thorax;  simul- 
taneously the  hood  enveloping  the  head  drops  by  a sternal  hinge. 
The  labellum  can  be  seen  still  pressing  upon  the  interior  of  the  hood 
as  the  head  emerges.  In  a minute  the  wings  are  rent  from  their 
envelopes  by  the  sturdy  pressure  of  the  legs,  which  have  slid  out  of 
their  sheaths  simultaneously  with  the  cleavage  of  the  thorax.  The 
legs  directly  assume  their  normal  position,  and  the  fly  walks  forth 
bodily,  spreading  its  plicated  wings.  The  liberated  wings  show  a 
clear  expanse  of  unwrinkled  membrane  which  at  first  is  soft  in  texture 
and  clear  lead-colored  throughout.  Finally  the  inflated  abdomen 
appears  in  the  dorsal  slit,  and  at  once  is  drawn  clear  of  the  encumber- 
ing puparium. 

The  time  from  the  appearance  of  the  head  to  the  evacuation  of  the 
puparium  requires  less  than  two  minutes.  This  time  is  increased  a 
minute  or  two  whenever  the  wing  sticks  to  the  lining  of  the  puparium, 
resulting  usually  in  a torn  wing. 

Directly  after  emergence  the  wings  are  shorter  than  the  body,  but, 
constantly  vibrating,  they  gradually  lengthen,  whereupon  they  be- 
come hardened  and  prepared  for  flight.  The  fly  does  not  spend  any 
time  preening  itself,  as  is  the  case  with  some  of  the  Muscidae  at  this 
stage.  The  time  prior  to  flight  is  spent,  however,  in  a clearing 
process.  This  begins  with  a copious  discharge  of  meconium  within 
three  to  five  minutes  after  emerging.  At  first  the  defecation  is  per- 
formed at  least  five  times  per  minute,  then  once  per  minute  for  a 
period  of  twelve  minutes.  At  the  end  of  this  time  the  excretions  be- 
come more  watery  in  character.  In  the  meantime  the  fly  walks 


162 


THE  EARLY  STAGES  OF  TABANLDiE 


about  in  a restless  manner,  constantly  vibrating  the  balancers  and 
flapping  its  wings,  while  the  distended  abdomen  becomes  reduced  to 
more  normal  proportions. 

The  meconium,  which  is  deposited  in  large  quantities,  is  pale  brown 
in  color,  rapidly  changing  to  amber,  then  becoming  clear.  The  pri- 
mary, heavier  excretion  appears  decidedly  oily  in  nature,  when 
examined  with  the  microscope. 

In  from  fourteen  to  twenty  minutes,  voluntary  flight  takes  place. 
This  is  at  first  tentative,  the  insect  alighting  upon  the  floor  about  a 
meter  distant.  After  a minute  of  rest,  flight  is  resumed,  the  fly 
escaping  through  the  open  window. 

The  puparium  left  behind  shows  certain  points  of  cleavage  which 
prove  to  be  very  constant.  There  is  a dorsal  slit  on  the  median  line 
of  the  thorax  which  extends  nearly  the  length  of  the  notum.  Another 
slit  extends  midway  across  the  orbital  region  through  the  genae  to 
the  wing  pouches.  A third  slit  extends  between  the  two  wing  en- 
velopes, and  a slight  one  behind  the  prothoracic  spiracular  tubercle. 

In  the  thirty- two  emergences  recorded,  the  males  preceded  the 
females  by  an  average  of  half  a day.  The  males  spent  from  three 
to  seven  days  in  the  pupal  stage,  averaging  five  and  one-half  days, 
while  this  period  required  four  to  nine  days  with  an  average  of  six 
days  in  the  female  flies. 

Bainb ridge  and  Fletcher  (1914)  observed  Tabanus  striatus  near 
Madras,  and  give  the  following  statements  which  may  serve  to  com- 
plement Mitzmain’s  work  in  as  far  as  it  seems  based  on  field  obser- 
vation : 

“Eggs  are  laid  in  a large  mass,  usually  on  a leaf  or  twig  overhanging  water 
into  which  the  young  larvae  drop  on  emergence,  thence-forward  leading  an 
aquatic  life  burrowing  in  the  mud  at  the  water’s  edge  and  feeding  on  worms  or 
living  or  dead  insects.  The  full  grown  larva  is  40  to  50  mm.  long,  dull  whitish, 
elongate,  tapering  at  each  end  with  protuberances  at  the  edges  of  the  segments. 
When  full  fed  it  leaves  the  damp  mud  at  the  water’s  edge  and  after  a quiescent 
period  pupates  in  the  earth  above  water-level.” 

An  egg  mass  of  Tabanus  striatus  on  a paddle  leaf  is  figured  (Plate 
2,  Figs.  22  and  23). 

Patton  and  Cragg  state  that  Tabanus  striatus  oviposits  as  a gen- 
eral rule  on  blades  of  grass,  pieces  of  stick,  etc.,  at  the  edge  of  a river, 
stream,  or  pond. 


WERNER  MARCHAND 


163 


The  larvae  are  said  to  be  powerful  swimmers  having  air  sacs  con- 
nected with  their  tracheal  tubes,  so  that  they  can  float  or  sink  at 
will. 

Large  numbers  of  egg  masses  are  regularly  destroyed  in  Madras 
by  a small  chalcid  parasite  which  was  not  identified. 

The  eggs  are  brownish  white  when  deposited  (Patton  and  Cragg). 

Tabanus  stygius  Say. — A species  of  the  Middle  and  Southern  States, 
recorded  from  Massachusetts,  New  Jersey,  Illinois,  Ohio,  etc.,  the 
life  history  of  which  is  comparatively  well  known  through  the 
observations  of  Hart  (1895)  and  Hine  (1906). 

On  its  oviposition  and  egg  Hine  is  the  first  to  give  us  information. 
The  species  oviposits  principally  on  the  leaves  of  Sagittaria  stand- 
ing in  shallow  water,  habitually  placing  the  eggs  just  above  the  point 
where  the  petiole  meets  the  expanded  part  of  the  leaf  (Plate  1,  Figs. 
3 and  4).27  The  precision  with  which  this  habit  is  followed  becomes 
a matter  of  interest.  Out  of  hundreds  of  masses  of  eggs  observed, 
only  a few  were  placed  on  other  species  of  plants  or  in  a different 
position  on  the  leaf  (Plate  1,  Fig.  5).  The  female  is  occupied  for  a 
half  hour  or  more  in  placing  the  several  hundred  eggs  composing  a 
single  mass,  and  during  this  time  the  observer  can  take  a position 
close  by  and  watch  the  proceedings  without  frightening  her  away, 
but  species  of  Tabanus  are  more  particular  about  the  approach  of 
intruders  than  are  various  Chrysops. 

The  egg  mass  is  white  when  first  placed  but  soon  turns  brown; 
it  is  convex,  and  is  composed  of  about  five  layers,  one  above  the  other. 
Individual  eggs  are  nearly  the  same  size  as  those  of  Tabanus  atratus , 
and  are  similar  to  them  in  form.  Hatching  as  observed,  occurred  in 
seven  days  after  oviposition.  From  a careful  study  of  microscopic 
sections  of  eggs  killed  as  soon  as  laid,  it  was  concluded  that  develop- 
ment does  not  begin  until  after  oviposition,  consequently  the  time 
given  is  the  entire  incubation  period. 

When  first  hatched  the  larvae  contain  a considerable  amount  of 
unused  yolk,  which  furnishes  them  food  for  a time;  it  is  therefore 
unnecessary  for  them  to  eat  anything  for  a few  days.  This  is  ad- 

27  The  leaf  represented  in  Fig.  4,  is  a leaf  of  Peltandra,  similar  in  shape  to  the 
Sagittaria  leaf  (Plate  1,  Fig.  3). 


164 


THE  EARLY  STAGES  OF  TABANID^E 


vantageous  no  doubt,  for  food  is  not  always  at  hand,  and  in  case  it 
is  not,  the  fact  that  nourishment  is  furnished  naturally  gives  them 
an  opportunity  to  investigate  their  surroundings. 

At  hatching  time  nearly  all  the  larvae  that  come  from  a single  mass 
of  eggs  appear  at  the  same  time  and  when  they  have  freed  themselves 
from  the  shells,  go  tumbling  down  into  the  water,  scattering  more  or 
less  and  sinking  to  the  bottom,  where  it  is  difficult  to  observe  their 
further  actions. 

Hine  found  that  small  catfishes  ( Ameiurus  melas ) are  enemies  of 
these  larvae,  and  he  observed  two  of  them  devour  200  young  larvae 
of  Tabanus  within  a few  hours. 

Hine’s  attempt  to  rear  the  larvae  from  the  egg  to  the  adult  was  not 
successful.  On  July  21,  a number  of  larvae  just  hatched  were  placed 
in  a breeding  jar  containing  damp  sand  covered  over  the  top  with  fine 
plant  material,  and  small  crustaceans  were  put  in  for  food.  The 
larvae  took  kindly  to  the  surroundings,  accepted  the  food  offered, 
and  began  to  grow  at  once.  After  about  two  weeks,  as  angleworms 
were  much  easier  to  obtain,  these  were  substituted  for  the  crustaceans, 
with  no  bad  effect  on  the  larvae,  which  continued  to  grow,  though 
rather  slowly.  The  largest  attained  a length  of  about  10  mm.  by  the 
beginning  of  winter,  when  they  ceased  eating.  They  appeared  to  be 
in  good  condition  in  the  spring,  but  for  some  reason  died  without 
further  increase  in  size. 

On  August  2,  of  the  same  year,  Hine  took  a large  larva  of  this 
species  in  Summit  County,  Ohio,  from  under  a flat  stone  along  a 
brook  that  ran  from  a spring.  When  taken  this  specimen  measured 
over  40  mm.  in  length  and  had  every  appearance  of  being  mature, 
but  it  continued  to  eat  the  angleworms  given  it  until  late  in  the 
fall.  It  then  ceased  feeding  until  the  following  spring,  when  it  took 
a small  amount  of  food  and  entered  the  pupal  stage  about  the  middle 
of  May,  the  adult,  a male,  issuing  June  14. 

Hine  thinks  that  it  is  hardly  possible  that  this  species  passes  all  its 
transformations  in  a single  year,  for  the  larvae  reared  from  eggs  were 
not  over  8 mm.  long  when  the  specimen  over  40  mm.  long  was  col- 
lected; and  as  the  latter  did  not  produce  the  adult  until  about  the 
normal  time  for  adults  to  appear  under  natural  conditions,  it  does 
not  seem  possible  that  the  first  mentioned  larvae  could  have  reached 
maturity  and  produced  adults  before  the  second  year. 


WERNER  MARCHAND 


165 


The  young  larva  is  briefly  described  by  Hines  as  follows: 

“Larva,  when  first  hatched,  4 mm.  long;  entirely  light  colored;  form  as  in 
older  specimens.  As  growth  continues  size  is  the  only  noticeable  change.” 

The  mature  larva  has  been  figured  and  described  in  detail  by  Hart 
(Plate  3,  Fig.  40).  This  species  was  the  most  abundant  tabanid 
larva  found  in  the  vicinity  of  Havana,  Illinois,  in  the  spring  of  1895. 
It  first  appeared  in  Hart’s  collections  September  14,  1894,  when  a 
number  were  noted  swimming  among  vegetation  near  the  margin  at 
Station  B,  on  the  wet  springy  shore  of  Quiver  Lake,  with  sandy 
and  muddy  ground,  grass,  and  coating  of  algae.  In  the  spring  they 
were,  however,  found  at  nearly  all  of  the  stations,  but  more  particu- 
larly in  connection  with  tipulid,  muscid,  and  Eristalis  larvae  in  matted 
accumulations  of  dead  stems  and  leaves  over  mud.  They  were  es- 
pecially abundant  on  March  30  in  Flag  Lake,  where  large  plump 
larvae  appeared  at  every  turn.  It  was  a surprise  to  find  a few  of  them 
upon  the  bottom  in  the  open  shallow  water,  far  from  shore,  in  the 
middle  of  Quiver  Lake  at  Station  A,  for  which  locality  Hart  gives  the 
characteristics:  “ Shallow,  mud  and  sand,  grass  and  floating  vegeta- 
tion, variable.”  Young  larvae  have  been  common  in  connection  with 
larvae  of  Bittacomorpha  and  Limnophila,  at  Station  I (see  Tabanus 
atratus)  since  March  17.  At  others  of  Hart’s  stations  they  have  been 
common  in  moist  drifts  of  fine  rubbish  washed  up  by  waves.  Pupae 
were  formed  in  the  breeding  cages  May  10  and  23.  One  emerged 
May  27,  and  another  tried  to  emerge  June  2,  but  died  and  was  re- 
moved from  its  case. 

The  larvae  of  Tabanus  stygius  resemble,  according  to  Hart,  those 
of  the  lineola  group  in  their  striation  and  coloration,  but  differ  in 
their  short  lateral  prothoracic  areas  and  larger  size.  They  are  like 
atratus  in  size,  but  may  be  readily  separated  from  it  by  their  coarser 
lateral  striation,  straw-yellow  tint,  slender  lateral  pigmented  stripes, 
and  usually  projecting  terminal  stigmatal  spine. 

Hart’s  description  of  the  mature  larva  follows: 

“Larva. — [Plate  3,  Fig.  40.]  Length  45-55  mm.,  diameter  6-7  mm.  Bright 
straw-yellow,  varying  in  some  young  larvae  to  nearly  clear  white;  marked  with 
light  fuscous  brown  microscopic  pubescence,  usually  paler  at  each  stage  than 
atratus .” 


166 


THE  EARLY  STAGES  OF  TABANID^E 


“Lateral  prothoracic  striated  areas  are  not  more  than  half  as  long  as  the  dorsal, 
striation  not  finer  than  that  of  the  middle  and  lower  lateral  areas  of  the  mesothorax, 
striated  portion  shining;  a small  smooth  spot  adjoining  the  impressed  line  below; 
remaining  upper  lateral  thoracic  areas  a little  less  coarsely  striated,  but  not 
strongly  different  from  that  of  the  prothorax;  abdominal  lateral  areas  a little  more 
finely  striate;  dorsal  and  ventral  areas  with  margins  striated,  disks  nearly  smooth 
in  adult  larvae,  last  segment  more  strongly  striate,  especially  beneath.” 

“Dark  annuli  distinct,  broad,  including  false  feet,  a distinct  transverse  dorsal 
and  ventral  pale  spot  in  front  of  the  false  feet;  abdominal  annuli  often  with  a 
small  triangular  backward  prolongation  on  median  line  above.  Prothoracic 
lateral  space  occupied  by  a pale  brownish  fuscous  quadrate  spot  in  front  of  the 
striated  space.  Meso-  and  metathoracic  lateral  stripes  usually  distinct,  but 
slender,  scarcely  dilated  posteriorly,  lateral  edges  of  dorsal  areas  diverging;  lateral 
stripes  of  abdomen  almost  wanting,  except  on  last  two  or  three  segments.  In 
these  stripes  the  punctures  of  the  upper  and  lower  rows  are  indicated  by  rounded 
pale  dots,  and  those  of  the  inner  rows  by  elongate  dots.  Last  segment  with  bases 
of  respiratory  tube  and  anal  prominence  encircled  with  dark  rings;  joined  by  a 
lateral  connection,  its  dorsum  with  at  most  a short  basal  line  or  pair  of  dots  on 
each  side.  Coarser  pubescence  of  false  feet  tipped  with  pale  brownish.” 

“Main  internal  tracheae  thick  and  noticeable,  especially  in  young  larvae, 
lustrous,  subparallel,  not  strongly  sinuate,  nearly  straight  posteriorly;  terminal 
stigmatal  spine  dark  reddish  brown,  smooth,  usually  protruded.” 

The  pupa  (Plate  11,  Fig.  125;  Plate  13,  Figs.  153  and  161)  has 
been  described  by  Hart  as  well  as  by  Hine,  both  of  whom  reared  the 
adult  from  pupae  obtained  from  adult  larvae  taken  in  nature.  The 
following  is  Hart’s  description. 

“ Pupa,  female. — Length  about  30  mm.,  diameter  about  6 mm.  Light  brownish 
fuscous,  thorax  paler,  shining,  abdomen  roughly  transversely  wrinkled,  and  sub- 
opaque. Palpal  sheaths  distinct,  as  far  apart  as  are  the  setae  borne  by  the 
larger  tubercles  at  the  center  of  the  anterior  surface  of  the  head  [Plate  13,  Fig. 
153];  surface  between  them  rounded,  bearing  a small  wrinkled  tubercle  at  middle; 
antennae  and  tubercles  darker  than  surrounding  surface;  ocellar  tubercles  dis- 
tinct; prothoracic  spiracular  tubercles  slightly  but  evenly  elevated  in  a plane 
parallel  to  that  of  the  surrounding  surface ; rima  nearly  straight  in  its  outer  half, 
inwardly  curving  strongly  forward,  and  ending  in  a conspicuous  hook;  free  mar- 
gin of  tubercle  rounded  at  tip.” 

“First  abdominal  with  two  distinct  setae  each  side  above  the  spiracles;  ab- 
dominal spiracular  tubercles  rounded,  broad  behind,  low-subhemispherical,  rima 
long,  following  posterior  border  of  tubercle,  slightly  curved  at  middle,  more 
strongly  curved  forwards  at  each  end;  on  anterior  surface  a transverse  groove 
extending  across  the  tubercle,  but  not  as  long  as  the  rima.  Fringes  of  unequal 


WERNER  MARCHAND 


167 


spines,  often  tipped  with  blackish,  all  but  two  of  the  long  spines  wanting  in  a 
broad  space  above  on  seventh  segment.  Terminal  teeth  [Plate  13,  Fig.  161] 
nearly  equal,  tipped  with  blackish,  their  points  marking  the  angles  of  a hexagon, 
slightly  wider  than  high.  Ventral  fringe  of  last  segment  not  webbed  together; 
lateral  tufts  high — on  a level  with  upper  lateral  line.” 

Hine’s  description  is  shorter: 

“Pupa  [Plate  11,  Fig.  125]  29  mm.  long;  color  dark,  approaching  fuscous; 
prothoracic  spiracle  strongly  bent  at  the  middle;  rima  oblique  and  straight  for 
the  outer  half  of  its  length,  remainder  gradually  curved,  with  a broad  hook  at 
the  inner  end.  Teeth  at  the  end  of  the  abdomen  [Plate  13,  Fig.  161]  six  in  num- 
ber, nearly  equidistant  from  one  another,  of  nearly  the  same  size,  with  the 
extreme  tips  slightly  turned  inward.” 

The  pupa  of  stygius  is,  according  to  Hine,  much  like  that  of  sulci- 
frons , but  there  is  some  difference  in  the  prothoracic  spiracles  and  in 
the  abdominal  teeth. 

Tabanus  sulcifrons  Macquart. — A North  American  species  inhab- 
iting Pennsylvania,  New  Jersey,  Ohio,  Illinois,  and  Louisiana. 
Closely  related  to  Tabanus  exul  and  abdominalis,  and  like  the  two 
latter,  appearing  late  in  the  season,  in  Ohio  abundant  in  the  latter 
part  of  July  and  all  of  August,  in  Louisiana  recorded  from  September 
7 to  October  16. 

Hine  has  made  many  interesting  observations  concerning  the  habits 
of  the  adult  flies  of  this  species,  but  was  unable  to  work  out  its  life 
history.  Although  the  eggs  were  procured  in  many  stages  of  de- 
velopment by  dissecting  the  females,  the  habits  of  oviposition  have 
not  been  observed.  The  form  of  the  eggs  and  the  number  produced 
by  a single  female  are  the  same  as  in  other  species  of  its  size.  Speci- 
mens containing  eggs  almost  fully  developed  were  taken  in  various 
places,  but  Hine  could  not  get  any  clue  as  to  where  oviposition  oc- 
curred by  dissectihg  the  females  where  they  were  collected,  as  he  had 
hoped  to  do. 

The  pupal  case  of  the  species  was  procured  by  locating  a female 
which  had  just  emerged.  The  place  where  this  pupal  case  was  taken 
was  on  a side  hill,  about  75  feet  above  the  bed  of  a small  stream. 
The  description  follows: 


168 


THE  EARLY  STAGES  OF  TABANID2E 


“Pupa. — [Plate  11,  Fig.  126;  Plate  13,  Fig.  165.]  Length  26  mm.,  diameter 
6 mm.  Color  yellowish  brown,  the  thorax  being  nearly  the  same  color  as  the  ab- 
domen. Tubercles  of  the  head  region  well  marked  and  distinctly  darker  than 
the  surrounding  parts.  Prothoracic  spiracular  tubercle  brown  in  color,  ele- 
vated, narrow,  ventral  half  oblique,  dorsal  half  turned  directly  forward,  thus 
forming  a distinct  bend  near  the  middle  of  the  length ; rima  nearly  straight  from 
outer  end  to  the  middle  and  evenly  curved  for  the  remainder  of  its  length,  inner 
tip  curved  backward,  thus  forming  a well-defined  hook.  First  abdominal  spiracle 
nearly  round ; its  rima  following  the  posterior  curvature,  very  narrow,  but  a little 
widened  above;  remaining  abdominal  spiracles  a little  smaller  than  the  first  one, 
each  with  a short,  slightly  curved  or  straight  rima.  Terminal  abdominal  segment 
[Plate  13,  Fig.  165]  with  several  small  spines  near  the  middle  of  its  length  and 
six  larger  spines  at  its  apex.  These  spines  are  all  brown  in  color,  with  the  apex  of 
each  approaching  black.  Six  apical  spines  of  nearly  the  same  size;  the  dorsal 
pair  point  upward,  outward,  and  slightly  backward,  the  lateral  one  on  each  side 
outward  and  backward,  while  the  ventral  pair  extend  almost  directly  backward. 
These  six  spines  mark  the  corners  of  a hexagon  with  nearly  equal  sides,  but  the 
ventral  pair  are  a little  nearer  together  than  the  dorsal  pair.” 

This  appears  to  be  all  that  we  know  about  the  early  stages  of  this 
species.  From  the  place  where  the  pupa  was  found,  the  larva  appears 
to  be  terrestrial  in  habit,  like  that  of  Tabanus  fronto , but  one  should 
bear  in  mind  that  possibly  the  young  larva  is  aquatic  and  leaves  the 
water  at  a later  stage  of  its  development. 

Tabanus  taniola  Palisot  de  Beauvois. — This  species  is,  according  to 
King,  the  most  common  and  most  widely  distributed  tabanid  found 
in  the  Anglo-Egyptian  Sudan,  and  the  most  frequently  accused  of 
causing  the  death  of  camels.  Occurring  on  the  White  Nile  as  far 
north  as  Dueim,  stray  specimens  have  occasionally  been  taken  in 
Khartoum.  King  was  able  to  secure  oviposition  in  captivity  in  this 
species  as  well  as  in  Tabanus  par , and  has  described  the  egg  and 
larva.  The  pupal  stage  is  not  known. 

In  order  to  secure  eggs,  gorged  females  were  taken  in  May,  on  cattle 
grazing  near  Bor,  and  placed  in  a breeding  cage  with  a dish  contain- 
ing grass  and  weeds  growing  in  mud  and  water.  They  were  fed  on 
sugar  and  water,  and  a few  batches  of  eggs  were  obtained.  A single 
egg  batch  was  taken  in  May  on  a blade  of  grass  overhanging  a dried 
up  water  pool  near  Kanissa  wood-station,  and  a number  of  batches  of 
eggs  were  collected  early  in  July  from  grasses  and  weeds  overhanging 
rain  pools  at  Gebelein. 


WERNER  MARCHAND 


169 


The  eggs  (Plate  1,  Figs.  8 and  9)  are  placed  by  the  female  fly  on  the 
upper  side  of  a blade  of  grass  or  some  similar  plant,  and,  with  the  excep- 
tion of  the  single  batch  taken  at  Kanissa  wood-station,  all  those  found 
were  overhanging  water.  An  unfinished  batch  of  eggs  resembles  an 
arrow-head.  The  eggs  are  closely  applied  to  each  other  and  left  bare, 
so  the  batch  can  easily  be  seen  when  freshly  laid,  owing  to  its  shin- 
ing white  to  yellowish  white  color.  Prior  to  hatching,  the  egg  mass 
becomes  darker.  According  to  King,  “the  egg  is  spindle-shaped, 
about  1.75  mm.  in  length  and,  when  first  laid,  is  white  in  colour. 
It  becomes  darker  as  the  embryo  within  develops.” 

The  eggs  obtained  in  the  breeding  cage  were  laid  on  May  24  to  25, 
and  hatched  on  May  29.  This  would  correspond  to  the  very  short 
incubation  period  of  four  to  five  days.  The  larvae  (Plate  1,  Fig.  9,  a) 
were  placed  in  glass  basins  containing  mud,  growing  grass,  and  water, 
and  were  offered  the  expressed  stomach  contents  of  female  ticks — 
Rhipicephalus  simus — taken  from  a dog.  They  fed  readily  on  this 
until  June  1 1,  when  they  were  placed  in  clean  river  sand  and  water,  and 
their  diet  was  changed  to  mosquito  larvae.  These  mosquito  larvae 
were  either  killed  or  laid  living  on  the  wet  sand  out  of  reach  of  the 
water,  in  which  position  the  tabanid  larvae  were  able  to  kill  them. 
In  water  the  mosquito  larvae  were  too  active  to  be  caught.  On  July 
16  their  food  was  changed  again  to  freshly  killed  and  bruised  earth- 
worms, and  these  they  also  ate  readily.  While  still  young  they  be- 
came vicious  cannibals,  and  consequently  each  larva  had  to  be  given 
a separate  dish.  They  were  brought  to  Khartoum  on  July  19  and  a 
few  days  later  it  was  noticed  that  the  majority  were  not  taking  their 
food.  They  were  then  nearly  if  not  quite  full  grown,  so  it  was  thought 
that  they  had  buried  themselves  in  the  sand  prior  to  pupating.  A 
thorough  search,  however,  revealed  the  fact  that  they  had  disappeared, 
and  it  was  not  until  later  that  mice  were  identified  as  the  cause  of  the 
loss.  The  two  remaining  larvae  were  then  killed  and  preserved.  It 
is  possible,  therefore,  that  the  larva  described  by  King  is  not  quite 
mature. 

The  larvae  of  Tabanus  tczniola  are  more  active  and  ferocious  than 
those  of  Tabanus  par , vigorously  attacking  any  other  larva  with 
which  they  may  come  in  contact.  They  have  not,  however,  the 
power  possessed  by  Tabanus  par  of  lying  dormant  in  the  soil  for  at 


170 


THE  EARLY  STAGES  OF  TABANIDiE 


least  fifty-seven  days  if  the  conditions  are  unfavorable  for  their 
development. 

King  describes  the  larva  somewhat  as  follows: 

“The  larva  [Plate  3,  Fig.  49],  when  fully  extended,  measures  about  29  mm. 
Color  white  to  grayish  white,  mandibles  black.  On  the  anterior  third  of  each 
abdominal  segment,  except  the  eighth,  is  a ring  of  pseudopods,  eight  in  each  ring 
— two  dorsal,  two  lateral,  four  ventral — except  on  the  first  abdominal  segment, 
where  the  dorsal  pair  is  wanting.  On  the  second  abdominal  segment  the  dorsal 
pair  is  very  strongly  developed.  The  ventral  pseudopods28  are  always  larger 
than  the  dorsal.  Each  pseudopod  bears  a crown  of  colorless  spines  or  hooks, 
and  between  the  pseudopods  there  are  also  spines  or  hooks,  often  darker  in  color, 
and  forming  a continuous  ring.  The  anus  is  situated  ventrally  at  the  base  of  the 
eighth  abdominal  segment  and  is  edged  with  dark  hairs.  On  either  side  of  the 
anus  is  a patch  of  dark  hairs,  roughly  kidney-shaped,  and  beyond  each  patch, 
laterally  placed  on  the  segment,  are  two  small  round  spots  of  dark  hair.  The 
syphon  tube  consists  of  two  segments,  and  when  exserted  is  shorter  than  the 
eighth  segment.  The  whole  surface  of  the  larva  is  more  or  less  shiny,  with  vary- 
ing longitudinal  striation,  the  areas  bearing  very  fine  striae  being  markedly  duller 
than  the  rest.  The  prothorax  has  the  dorsal  area  smooth  in  the  anterior  two-thirds 
and  rather  coarsely  striate  posteriorly ; the  ventral  area  is  almost  entirely  smooth 
and  divided  in  two  by  a medium  furrow;  the  two  lateral  areas  are  finely  striated  in 
the  basal  third  and  more  coarsely  so  in  the  anterior  parts.  The  mesothorax  has 
the  dorsal  and  ventral  areas  smooth  and  shining  in  the  anterior  two-thirds,  and 
rather  coarsely  striate  posteriorly,  the  ventral  area  having  no  furrow;  the  lateral 
areas  are  a little  more  finely  striate  than  those  of  the  prothorax,  and  there  is 
a rather  broad  dull  non-striated  band  at  both  the  anterior  and  posterior  margins. 
Similar  dull  bands  occur  on  the  metathorax  and  the  abdominal  segments,  but  com- 
pletely encircling  the  segments.  The  abdominal  segments  1 to  7 have  the  dorsal 
and  ventral  areas  moderately  shining,  and  the  striation  is  rather  coarse  and  irreg- 
ular; the  lateral  areas  appear  much  duller,  owing  to  the  extreme  fineness  of  the 
striation.  On  the  eighth  abdominal  segment  the  striae  are  moderately  well 
marked  and  of  similar  appearance  on  all  the  faces.” 

The  pupa  of  Tabanus  tceniola  is  not  known.  From  the  egg  mass  a 
natural  enemy  parasite  was  obtained  by  King,  adding  hereby  one 
more  example  to  the  cases  of  egg  parasitism  observed  in  tabanids. 
These  small  Hymenoptera  were  bred  from  an  egg  mass  of  Tabanus 
tceniola,  taken  at  Gebelein.  The  species  had  not  yet  been  identified 
at  the  time  when  King’s  report  appeared,  but  figures  were  given,  to- 
gether with  the  parasitized  egg  mass,  showing  the  exit  hole  of  the 


28  See  p.  108,  foot-note  18. 


WERNER  MARCHAND 


171 


parasites.  To  judge  from  the  illustration  it  might  be  a species  of 
Phanurus , but  as  the  figures  are  life  size,  not  much  can  be  seen  of 
structural  details. 

As  elsewhere  in  tropical  Africa,  this  is  probably  the  commonest 
species  of  the  genus  in  the  Mlanje  district,  where  Neave  bred  it  also 
from  larvae. 

The  larva  is,  according  to  Neave,  chiefly  remarkable  for  its  white 
color  and  lack  of  pigment,  and  for  the  presence  of  a row  of  bristles 
immediately  anterior  to  the  anus.  It  is  one  of  the  most  active  and 
restless  species  Neave  had  to  deal  with. 

Tabanus  ( Neotabanus 24)  tricmgulum  Wiedemann. — This  Brazilian 
species  was  reared  by  Lutz,  at  Manguintros,  Brazil,  in  February, 
1914,  from  full  grown  larvae,  which  were  obtained  by  sifting  the  mud 
from  the  edges  of  a small  brook  (together  with  those  of  Neotabanus 
ochrophilus) , and  breeding  in  damp  moss.  No  morphological  dif- 
ferences were  observed  between  this  species  and  Tabanus  ochrophilus. 

Tabanus  trimaculatus  Palisot  de  Beauvois. — A species  occurring  in 
the  middle  and  southern  states  west  to  Kansas  (Hine).  We  possess 
very  few*  data  on  its  early  stages. 

Hine  mentions  (1903)  that  he  has  been  in  possession  of  the  eggs, 
in  connection  with  his  studies  on  extermination  of  tabanids  by  col- 
lecting and  destroying  the  eggs.  By  counting  it  was  found  that 
twenty  egg  masses  of  Tabanus  trimaculatus  averaged  over  500  eggs 
each. 

Brimley  found,  on  April  15,  1909,  two  larvae  of  Tabanus , under  the 
bark  of  a soggy  log  which  was  an  inch  or  two  above  the  water.  One 
died;  the  other  was  put  into  a bottle  with  some  wet  dirt  and  rotten 
wood,  and  “from  this  a male  of  Tabanus  trimaculatus  was  bred  on 
May  18  of  the  same  year.  The  larva  that  died  and  which  was 
presumably  the  same  species  was  preserved  in  alcohol.  It  measures 
37  mm.  in  length  and  is  white  without  markings.”29 

Tabanus  tropicus  Linne. — A species  found  in  Europe  (Laibach  and 
Trieste,  according  to  Schiner),  but  also  in  India  (same  species?)  and 
here  said  to  be  a carrier  of  surra  (Neveu-Lemaire). 

29  In'  the  meantime,  I have  repeatedly  found  the  larvae  in  Princeton  (1917) 
and  bred  the  adult. 


172 


THE  EARLY  STAGES  OF  TABANID^E 


Scholtz  (1850)  reports  that  he  has  found  the  pupae,  together  with 
those  of  Tabanus  autumnalis  and  of  Hcematopota  pluvialis  in  the 
neighborhood  of  Breslau  in  June,  1850,  at  the  edge  of  a pond  cov- 
ered with  Lenina,  the  water  of  which  was  polluted  from  manure  piles 
surrounding  it.  The  pupae  were  found  near  the  edge  under  a thick 
mass  of  moist  Lemna,  together  with  Stratiomys — and  Syrphus — 
pupae;30  the  flies  hatched  after  a few  days. 

Tabanus  ustus  Walker. — An  African  species,  observed  by  Neave  in 
enormous  numbers  around  a pool  in  a nearly  dry  stream  bed,  on  the 
plains  in  Portuguese  territory,  southern  Nyasaland. 

One  male  and  three  females  were  bred  in  the  laboratory  at  the  end 
of  October  a;nd  beginning  of  November.  The  larva,  of  which  the 
terminal  segments  are  figured  (Plate  5,  Fig.  66),  resembles  that  of 
Tabanus  biguttatus , but  is  less  pigmented. 

The  upper  hooks  of  the  pupal  aster  are  considerably  larger  than  the 
remainder.  The  spines  of  the  dorsolateral  comb  are  much  reduced, 
especially  in  the  male. 

The  pupal  aster  of  the  male  and  the  dorsolateral  comb  of  both  sexes 
are  figured  (Plate  14,  Fig.  177,  a,  b,  c). 

Tabanus  variabilis  Loew. — An  African  species,  not  rare  near  Mt. 
Mlanje,  southern  Nyasaland,  on  wooded  streams  in  the  neighborhood 
of  the  mountain  in  October  and  November,  occasionally  later. 

The  larvae  were  found  in  this  locality  by  Neave,  in  abundance. 
They  are  entirely  different  from  those  of  Tabanus  atrimanus,  being 
almost  colorless,  though  in  quite  mature  individuals  the  base  of  the 
syphon  and  the  syphon  itself  are  of  an  orange  color.  The  most  strik- 
ing peculiarity  of  this  larva  is,  however,  the  presence  of  a distinct 
papilla  of  a dark  color  on  each  side  of  the  anal  segment.  This  is 
easily  recognizable  in  life  and  distinguishes  this  species  from  any 
other  seen  by  Neave.  The  anus  is  also  unusually  prominent. 

The  pupa  is  also  remarkable  for  its  dark  coloration,  especially  on 
the  dorsum  of  the  thorax.  The  aster  is  characterized  by  the  large 
horizontally  extended  middle  pair  of  hooks,  and  its  outline  is  there- 
fore entirely  different  from  that  of  the  closely  allied  Tabanus  atri- 

30  See  also  pp.  72  and  91. 


WERNER  MARCHAND 


173 


manus.  The  dorsolateral  comb  consists  of  a few  short  and  rather 
stout  spines. 

Figures  are  given  of  the  syphon  of  the  larva  (Plate  5,  Fig.  70),  the 
pupa  (Plate  12,  Fig.  138),  pupal  aster,  and  dorsolateral  comb  of  both 
sexes  (Plate  14,  Fig.  176,  a-d). 

Tabanus  virgo  Wiedemann. — A small  species,  recorded  for  Bengal 
and  South  India.  On  its  early  stages  we  possess  notes  through  the 
work  of  Patton  and  Cragg. 

As  in  all  the  small  tabanids  observed  by  these  authors,  the  eggs  are 
laid  on  blades  of  grass  just  at  the  edge  of  a shallow  stream,  or  on  the 
leaves  of  the  lotus  plant  at  the  edges  of  small  ponds,  but  never  over 
deep  water.  The  larvae,  as  in  the  other  small  species,  are  said  to 
have  no  air  sacs,  and  to  die  when  falling  into  deep  water. 

The  mature  larva  of  Tabanus  virgo  is  figured  by  the  same  authors 
(Plate  4,  Fig.  63).  Attention  is  called  to  the  openings  of  the  tracheae 
being  flush  with  the  body.  In  fact  the  syphon  is  extremely  short 
when  compared  with  that  of  Tabanus  bicallosus,  while  as  shown  in  the 
figures,  in  Tabanus  ditceniatus  it  is  of  medium  length.  On  the  figure 
given,  the  larva  of  Tabanus  virgo  shows  no  striation  or  color  pattern, 
but  the  mouth-parts  appear  larger  than  in  the  other  species,  and  the 
prolegs  are  large,  fleshy,  and  somewhat  modified. 

A small  egg  mass  of  this  species  is  figured  (Plate  1,  Fig.  16)  as  laid 
on  a dry  twig,  and  consisting  of  only  five  eggs,  attached  to  a twig 
which  in  fact  is  much  smaller  in  diameter  than  the  eggs  themselves. 

The  pupa  is  figured  (Plate  11,  Fig.  134)  by  Patton  and  Cragg,  and 
in  addition,  an  enlarged  figure  of  the  eighth  abdominal  segment  of 
the  pupa  is  given  (Plate  12,  Fig.  146),  showing  the  six  terminal  teeth 
and  their  arrangement. 

Tabanus  vivax  Osten  Sacken. — A North  American  species  which 
apparently  is  never  very  plentiful,  but  has  been  taken  in  a number 
of  the  eastern  states  (New  York,  Maine,  Ohio,  etc.).  In  Ohio  it  is  on 
the  wing  during  the  last  half  of  June. 

The  life  history  has  been  worked  out  by  Hine.  The  eggs  are  de- 
posited in  masses  composed  of  several  hundreds,  on  stones  that  pro- 
ject above  the  water  in  riffles  of  streams.  The  egg  mass  is  nearly 
round  in  outline,  only  slightly  convex,  composed  of  about  three 


174 


THE  EARLY  STAGES  OF  TABANIDiE 


layers  one  above  the  other.  The  color  of  the  whole  mass  is  brown, 
mottled  over  the  top  with  white.  In  these  respects  they  do  not 
differ  in  particular  from  the  eggs  of  other  species  of  the  genus,  but  the 
masses  observed  were  not  so  convex  as  those  of  Tabanus  atratus,  and 
being  placed  on  stones  of  a color  similar  to  themselves  are  rather 
difficult  to  see.  Females  have  been  observed  ovipositing  as  early  as 
June  8,  but  most  often  eggs  are  deposited  after  this  date. 

The  larvae  (Plate  3,  Fig.  43)  occur  in  the  streams  in  the  fall.  Hine 
states  that  in  September  and  October  each  year  they  collected  the 
larvae  of  the  dobson-fly  ( Corydalis  cornuta  L.)  for  study  in  the  lab- 
oratory. By  turning  stones  at  the  edge  of  swift  riffles,  or  by  means 
of  a net  stretched  across  the  riffles  to  catch  such  specimens  as  are 
dislodged  by  turning  stones  behind  the  net  in  the  stream,  in  addi- 
tion to  Corydalis  larvae,  a large  number  of  the  larvae  of  this  horse-fly 
were  found.  Though  having  done  much  collecting  in  streams,  Hine 
asserts  that  the  larva  of  Tabanus  vivax  is  the  only  tabanid  larva 
taken  in  riffles  so  far.  It  was  not  found  difficult  to  rear  these  larvae. 
Larvae  taken  late  in  the  fall  were  placed  in  damp  sand  and  fed  on 
angleworms.  As  winter  approaches  they  refuse  to  eat  and  remain 
quietly  in  the  sand  until  the  following  spring;  then  they  feed  actively 
for  a few  days  and  change  to  pupae.  They  reach  the  adult  stage  in 
late  spring  or  early  summer.  Like  other  tabanid  larvae,  the  larvae  of 
Tabanus  vivax  are  not  particular  as  to  their  food;  all  that  appears  to 
be  necessary  is  that  they  obtain  small  soft  bodied  animals.  Crus- 
taceans serve  them  as  well  as  insects  and  their  own  species  as  well  as 
some  other  species — whatever,  in  fact,  is  in  the  sand  of  the  breeding 
cage. 

Hine  has  never  observed  the  larvae  in  nature  in  the  spring;  conse- 
quently their  habits  at  this  time  of  the  year  are  not  exactly  known, 
but  Hine  supposes  that  they  leave  the  water  and  pupate  in  the 
earth  near  at  hand. 

Hine’s  description  of  the  larva  and  pupa  follows: 

“Larva. — [Plate  3,  Fig.  43.1  When  full  grown,  about  25  mm.  long.  Gen- 
eral color  yellowish  white,  anterior  margin  of  each  thoracic  segment  and  a narrow 
band,  including  the  prolegs,  on  the  anterior  half  of  the  first  seven  abdominal 
segments  opaque,  and  appearing  darker  than  the  other  parts,  which  are  more  or 
less  shining  and  usually  finely  striate  longitudinally.  Prothoracic  segment  di- 


WERNER  MARCHAND 


175 


vided  by  longitudinal  grooves  into  four  nearly  equal  parts,  which  may  be  called 
the  dorsal,  ventral,  and  lateral  areas.  The  lateral  areas  are  shining  and  finely 
striated  on  the  posterior  third  and  opaque  on  the  anterior  two-thirds;  the  dorsal 
and  ventral  areas  are  opaque  on  about  the  anterior  fourth  and  distinctly  shining 
on  the  remaining  parts.  The  ventral  space  is  plainly  divided  into  two  equal  parts 
by  a longitudinal  groove.  In  order  to  see  the  character  of  this  segment,  it  must 
be  fully  extended.  The  mesothoracic  and  metathoracic  segments  have  a num- 
ber of  longitudinal  grooves,  some  of  which  are  very  narrowly  bordered  by  opaque 
darker  coloring,  which  proceeds  backward  from  the  narrow  anterior  border  of 
these  segments.  Each  of  the  first  seven  abdominal  segments  has  on  its  anterior 
part  a transverse  row  of  eight  tubercles  which  encircles  the  segment.  These  all 
bear  short  spines  or  claws  at  the  apex,  excepting  a dorsal  pair  on  each  of  the  first 
three  or  four  segments.  They  may  be  called  prolegs,  since  they  have  the  parts 
necessary  to  such  organs  and,  what  is  more,  are  used  as  prolegs.  On  the  poste- 
rior dorsal  border  of  most  of  the  abdominal  segments  there  may  be  a narrow, 
irregular,  opaque  marking  of  the  same  color  of  the  narrow  band  in  the  region  of 
the  prolegs;  eighth  segment  on  each  side  with  two  narrow,  curved  markings  which 
have  the  appearance  of  being  composed  of  contiguous  punctures.  These  mark- 
ings are  of  the  same  shade  of  color  as  the  other  darker  areas,  and  the  lower  one 
is  more  than  twice  as  long  as  the  upper.” 

11  Pupa. — [Plate  11,  Fig.  128.]  18  mm.  long  and  4 mm.  in  diameter.  Light 

brown  in  color,  thorax  somewhat  paler  than  the  abdomen.  Antennal  and  other 
tubercles  of  the  head  and  thorax  prominent  and  darker  than  the  surrounding 
parts.  Prothoracic  spiracular  tubercle  slightly  elevated,  reniform,  oblique;  rima 
uniformly  curved  for  nearly  its  whole  length;  but  just  before  the  anterior  end  the 
curvature  is  stronger,  although  no  hook  is  formed.  First  abdominal  spiracle 
nearly  round;  rima  almost  uniformly  curved,  posteriorly  very  slightly  widened 
just  at  the  end,  anteriorly  slightly  narrowed  and  curved  so  as  to  form  a short 
hook.  The  other  abdominal  spiracles  agree  with  the  first  one  in  general,  but 
there  is  slight  variation  in  the  enlargement  and  curvature  of  the  extreme  ends. 
Terminal  teeth  [Plate  13,  Fig.  160]  prominent,  shining  brown  in  color,  darkest 
at  the  extreme  tips.  Dorsal  pair  of  teeth  smallest  and  closer  together  than 
the  ventral,  lateral  teeth  longer  and  larger  than  the  ventral  and  located  much 
beneath  the  dorsal,  in  fact  they  are  nearly  midway  between  the  dorsal  and 
ventral.” 


UNIDENTIFIED  SPECIES  OF  TABANUS. 


Tabanus  sp.  Nos.  1 and  2. — Following  Mann’s  observations,  Kollar 
succeeded  in  finding  freshly  laid  eggs  of  another  species  of  Tabanus , 
which  was  not  determined,  in  a damp  meadow  at  Dornbach  near 
Vienna,  of  which,  after  nine  days,  similar  larvas  hatched  as  were 
obtained  from  the  egg  masses  from  Wippach,  of  Tabanus  quatuorno- 
tatus.  Kollar  also  found  a parasitic  wasp  ovipositing  in  the  Tabanus 
eggs;  this  wasp  was  found  to  be  specifically  different  from  that  ob- 
tained from  the  eggs  of  quatuornotatus . 

At  about  the  same  time  eggs  of  another  undetermined  species 
were  found  by  Hofmann,  quoted  by  Kollar.  No  descriptions  are 
given. 

Tabanus  sp.  No.  3. — Riley  and  Johannsen  (1915)  give  a photo- 
graphic illustration  of  the  egg  mass  of  an  American  species  of  Tabanus , 
the  name  of  which  is  not  given  (Plate  1,  Fig.  6). 

Tabanus  sp.  No.  4. — (Hart’s  sp.  a .)  Two  examples  of  larvae 
of  this  peculiar  species  have  been  collected  by  Hart,  from  diverse 
situations.  One  was  taken  under  bark  in  woods  near  Urbana,  Illi- 
nois, April  6;  the  other,  from  a prairie  ditch,  in  Kane  County,  Illinois, 
which  was  swollen  by  a heavy  rain.  Hart’s  description  is  as  follows: 

“Larva. — Length  19  mm.,  diameter  2.5  mm.  Last  antennal  joint  short  and 
very  slender,  epistoma  not  silicate  anteriorly,  but  with  an  elongate  puncture. 
Whitish,  lateral  pubescent  stripes  wanting,  annuli  much  reduced  and  pale  except 
upon  false  feet.  Prothorax  shining,  with  anterior  opaque  annulus ; lateral  areas  as 
long  as  the  dorsal,  their  upper  and  lower  thirds  rather  coarsely  striate,  middle  third 
smooth,  with  several  punctures;  ventral  area  smooth,  middle  groove  with  three 
striae,  dorsal  area  nearly  smooth.  Striae  of  upper  lateral  spaces  of  meso-  and  meta- 
thorax and  of  dorsal  and  ventral  areas  of  abdomen  moderately  coarse;  those  of 
lateral  area  of  abdomen  somewhat  finer;  dorsal  and  ventral  areas  of  mesothorax 
with  a few  striae;  of  metathorax  rather  sparsely  striate.  All  areas  more  or  less 
shining.  On  the  anterior  side  of  each  dorsal  false  foot,  at  its  outer  end,  an 
opaque  light  brown  elongate  fleck.  False  feet  shining  and  rather  finely  striated 
on  each  side.  No  projecting  spine  posteriorly;  only  a narrow  pale  annulus  on 
last  segment,  at  base  of  breathing  tube.” 

176 


WERNER  MARCHAND 


177 


Tabanus  sp.  No.  5. — (Hart’s  sp.  b.)  Hart  reports  that,  in  col- 
lecting the  larvae  of  Limnophila  and  Bittacomorpha  in  the  swampy 
slough  of  Station  I,  many  small  tabanid  larvae  were  found  in  the  mud 
and  debris,  and  among  them  occurred,  on  April  15,  two  examples  of  a 
distinct  very  white  form  with  faint  markings  like  those  of  stygius, 
but  laterally  striate  more  like  atratus,  and  with  a conspicuous  isolated 
smooth  spot  in  the  lateral  striated  area  of  the  prothorax.  He  de- 
scribes .the  larva  as  follows : 

“Larva. — [Plate  3,  Fig.  42.]  Length  22-23  mm.,  width  2.5  mm.  Very  pale 
whitish,  markings  like  those  of  stygius , but  pale  yellowish  fuscous  and  incon- 
spicuous. Head  pale  brownish.” 

“Lateral  prothoracic  areas  not  more  than  half  as  long  as  the  dorsal,  striation 
scarcely  visible,  microscopically  fine  and  opaque,  much  finer  than  that  of  the 
middle  and  lower  lateral  areas  of  the  mesothorax,  which  are  somewhat  shining;  a 
rather  large  smooth  spot  included  in  the  striated  lateral  area  of  the  prothorax, 
not  far  from  the  shining  ventral  area  but  entirely  isolated  from  it;  remaining 
upper  lateral  thoracic  areas  distinctly  more  coarsely  striated  than  the  areas  be- 
low them,  and  quite  shining;  abdominal  lateral  areas  more  finely  striate,  feebly 
shining,  microscopically  striate  on  the  posterior  portion  of  each  area.  Dorsal 
and  ventral  areas  shining,  with  sparse  marginal  striae  interrupted  on  the  disks, 
those  of  thorax  especially  smooth.” 

“Dull  annuli  broad,  including  the  false  feet,  a distinct  transverse  dorsal  and 
ventral  pale  spot  in  front  of  the  false  feet.  Lateral  prothoracic  area  occupied  by 
a very  pale  fuscous  opaque  quadrate  spot  in  front  of  the  striated  area.  Meso-  and 
metathoracic  lateral  stripes  usually  visible,  but  slender,  not  dilated,  lateral  edges 
of  dorsal  areas  diverging;  lateral  stripes  of  abdomen  almost  wanting,  except  on  last 
two  or  three  segments.  Last  segment  with  bases  of  respiratory  tube  and  anal 
prominence  ringed  with  opaque  fuscous,  that  around  anal  prominence  sending 
up  an  indistinct  stripe,  with  posterior  extensions.  Pubescence  of  false  feet 
whitish  or  pale  fuscous.  Respiratory  tube  slender,  no  spine  protruding.” 

Tabanus  sp.  No.  6. — Malloch  (1917)  describes  briefly,  and  without 
illustrations,  an  unknown  tabanid  larva,  which  differed  from  other 
larvae  he  had  before  him,  in  being  entirely  white  and  without  lines  or 
patches  of  pubescence,  as  well  as  in  being  more  robust,  and  less 
tapered  at  the  extremities.  In  general  appearance  it  very  closely 
resembled  an  asilid  larvae,  the  resemblance  being  accentuated  by  the 
small  size  of  the  locomotor  organs;  and  it  stood  as  “Asilidae”  in  the 
Illinois  State  Laboratory  collection.  The  specimen  was  obtained  in 
Pulaski,  Illinois,  June  1,  1910,  in  a pit-cage  used  in  rearing  white 


178 


THE  EARLY  STAGES  OF  TABANIDiE 


grubs.  This  is  a surprising  occurrence,  as  most  of  the  species  of 
Tabanus  are  confined  to  damp  ground  or  to  aquatic  surroundings. 

In  his  analytical  key,  Malloch  gives  the  following  characteristics  of 
this  larva,  “Body  without  markings  either  of  color  or  hairs.  Body 
very  closely  and  finely  striated,  entirely  white.”  The  size  of  the 
larva  is  not  given. 

Tabanus  sp.  No.  7. — Unknown  European  species,  observed  by 
Surcouf  and  Ricardo  (1909).  Only  the  pupa  is  figured  (Plate  12, 
Fig.  150). 

Larva. — Surcouf  and  Ricardo  have  reported  on  the  capture  and 
rearing  of  a tabanid  larva,  of  which,  however,  the  species  was  not 
determined.  Roubaud  had  given  them  “a  young  larva  of  Tabanus” 
which  he  had  collected  on  October  3,  1905,  at  Meudon  in  the  muck 
of  a pond;  this  larva  was  reared  for  eight  months  in  water,  feeding 
not  on  living  prey  but  on  organic  matter  introduced  with  a bunch 
of  moss  which  covered  the  bottom  of  the  crystallizing  dish  in  which 
it  was  kept.  On  May  13,  1907,  it  was  seeking  a protected  place  in 
this  moss,  lost  its  mobility,  turned  more  translucent  than  usual, 
and,  on  May  16,  had  transformed  into  a pupa,  which,  unfortunately, 
perished  in  consequence  of  an  accident.  The  larva  is  described  as 
elongate,  whitish,  very  active,  pointed  at  both  ends,  and  provided 
with  a sort  of  crested  ring  on  each  of  its  segments;  these  rings  are 
equipped  all  along  their  course  with  retractile  tubercles  serving  as 
means  of  locomotion. 

Pupa  (Plate  12,  Fig.  150). — The  pupa  which  Surcouf  and  Ricardo 
obtained  from  this  larva  measured  17  mm.  in  length  and  4 mm.  in 
diameter.  This  pupa  has  the  aspect,  according  to  the  authors,  of  a 
lepidopterous  pupa;  the  upper  anterior  part  was  smooth  above,  com- 
prising the  thorax  and  head,  the  lower  anterior  parts  bearing  under 
their  chitinous  coverings,  the  antennae,  the  palpi,  the  eyes,  and  the 
first  pair  of  legs.  The  wings  are  contained  in  a case  which  reaches 
the  top  of  the  scutellar  segment,  unarmed.  The  posterior  region  of 
the  pupa  comprises  seven  segments  which  have  at  the  tip  a crown  of 
rigid  hairs  intermingling  with  pointed  tubercles  with  enlarged  bases. 
The  last  segment  has  two  tubercles,  each  one  consisting  of  three 
irregular  more  or  less  curved  spines.  The  third  thoracic  segment 
and  the  first  six  abdominal  segments  all  have  a spiracle  on  each  side. 


WERNER  MARCHAND 


179 


These  spiracles  appear  slightly  projecting  above  the  surface. 

Tabanus  sp.  No.  8. — An  unidentified  African  species.  No  de- 
scription but  good  illustration  of  ventral  and  dorsal  aspect  of  larva 
is  given  by  Brumpt  (1910).  The  larva  shows  dorsal  prolegs  well 
developed  which  indicates  an  aquatic  mode  of  life  (Plate  4,  Fig.  55, 
a , b,  c). 

Tabanus  sp.  No.  9. — Unidentified  African  species  of  which  a poor 
illustration  is  given  by  Griinberg  (1907),  (Plate  4,  Fig.  58). 

Tabanus  sp.  No.  10. — A young  specimen  of  an  unidentified  Euro- 
pean species  is  figured  by  Graber  in  his  work  on  the  chordotonal 
organs  (1882-83)  (Plate  8,  Fig.  99);  it  is  supposed  to  belong  to 
Tabanus  autumnalis , and  may  belong  to  Chrysops.  (See  also  page 
23.) 

Tabanus  sp.  No.  11. — Henneguy  (1904)  gives  the  illustration  of  a 
young  Tabanus  larva  (Plate  10,  Fig.  109),  with  typically  inflated 
tracheal  trunks,  in  Europe.  (See  also  pages  36  and  38.) 

Tabanus  sp.  No.  12. — Paoli  (1907)  gives  an  illustration  of  the  larva 
(Plate  10,  Figs.  Ill  to  116)  in  which  he  studied  Graber’s  organ. 
Though  this  larva  is  supposed  to  belong  either  to  Tabanus  cordiger  or 
to  Tabanus  autumnalis , it  is  not  unlikely  that  it  is  another  species. 
The  two  species  mentioned  happened  to  be,  with  Tabanus  bovinus 
and  Tabanus  quadrinotatus , and  one  or  two  others,  the  only  European 
species  which  had  been  found  in  the  larval  state  up  to  that  date, 
but  the  descriptions  are  all  insufficient. 

The  larvae  which  were  studied  by  Paoli  live  in  slow  flowing  rivers, 
especially  in  the  soft  mud  containing  decomposing  organic  matter, 
among  the  algae,  especially  Characece , which  grow  in  the  water,  in 
places  where  they  can  easily  utilize  the  atmospheric  air  as  they  are 
not  provided  with  organs  adapted  to  locomotion  in  water. 

The  body  consists  of  thirteen  distinct  segments,  of  which  one  is  the 
head,  three  belong  to  the  thorax,  and  nine  to  the  abdomen;  the  tenth 
segment  of  the  abdomen  is  much  reduced  and  fused  with  the  ninth; 
the  eleventh  is  absent. 


180 


THE  EARLY  STAGES  OF  TABANIDiE 


Graber,  as  Paoli  mentions,  gives  his  larva  (in  the  figure)  erro- 
neously, only  ten  segments,  while  it  is  known  that  the  larvae  of  Diptera 
have  fourteen  segments,  of  which  the  last  one  is  vestigial. 

The  largest  specimens  of  the  larvae  examined  are,  when  completely 
extended,  30  to  32  mm.  in  length.  The  body  is  fusiform  (Plate  10, 
Fig.  Ill),  the  color  a dirty  yellowish  white,  the  head  is  elongate, 
retractile;  the  three  thoracic  segments  do  not  present  any  peculiari- 
ties. The  first  seven  abdominal  segments  are  furnished  each  one 
with  eight  papillae,  arranged  all  around  the  anterior  third  of  each  seg- 
ment, which  consequently  in  cross-section  presents  itself  with  eight 
prominences  arranged  like  the  corners  of  a regular  octagon.  These 
papillae  are  retractile,  and  each  of  them  is  furnished  at  the  tip  with 
numerous  strong  hooklets.  The  larva  moves  in  the  mud  and  among 
the  algae,  in  addition  to  making  worm-like  movements  due  to  the  con- 
tractions of  the  subcutaneous  muscular  stratum,  also  by  protracting 
and  retracting  the  fifty-six  papillae  which  in  this  way  form  a support 
and  assure  to  the  larva  its  locomotion.  The  eighth  segment  bears 
on  its  ventral  side  a thick  sulcate  prominence,  in  the  middle  of  which 
the  opening  of  the  anus  is  situated.  Anterior  to  this  prominence  a 
large  lip-like  expansion  is  formed,  with  numerous  strong  hooklets 
which  are  curved  forward  at  the  free  margin.  Behind  the  anal 
opening  the  eighth  segment  is  narrow  and  curved  upwards;  the 
ninth  segment  is  short,  cylindric,  thin,  more  or  less  retracted  into  the 
inside  of  the  eighth,  bearing  at  its  extremity  the  rudiments  of  the 
tenth,  in  which  the  two  stigmata  open. 

Paoli,  after  thus  briefly  describing  the  larvae,  adds  that  when  dis- 
turbed by  contact  or  pressure,  they  undergo  contortions  in  every  di- 
rection, making  a sound  like  the  crackling  of  small  electric  sparks. 
They  feed  on  animal  matter  and  ferociously  attack  small  larvae  of 
other  aquatic  insects,  and  also  devour  one  another;  when  they  are 
attacking  one  another  the  crackling  sounds  are  heard  repeatedly. 
For  the  description  of  Graber’ s organ  in  these  larvae  see  page  29  and 
following. 

Tabanus  sp.  No.  13. — Maxwell-Leffroy  and  Howlett  (1909)  give,  on 
a colored  plate,  illustrations  of  the  egg  mass,  young  larva,  full  grown 
larva,  pupa,  and  an  ichneumonid  parasite  of  an  unidentified  Indian 


WERNER  MARCHAND 


181 


species  of  Tabanus.  The  egg  mass  (Plate  1,  Fig.  7)  is  yellow  in  the 
original  and  not  very  convex  in  structure.  The  young  larva  (Plate 
5,  Fig.  76,  a),  is  whitish  and  semitransparent.  The  full  grown  larva 
(Plate  5,  Fig.  7 6,  b)  is  yellow,  its  natural  size  47  mm.  The  pupa  is 
yellow  in  color,  the  thorax  grayish  (Plate  12,  Fig.  139).  The  hymen- 
op  terous  parasite  figured  (Plate  5,  Fig.  76,  c)  is  the  only  parasite 
of  this  (ichneumonid)  type  observed  so  far  as  a tabanid  parasite, 
the  other  being  cases  of  Proctotrupidae. 

Tabanus  sp.  No.  14. — Only  the  pupa  of  this  Indian  species  (no 
name  given)  is  figured  by  Maxwell-Leffroy  and  Howlett  (1909)  (Plate 
11,  Fig.  132). 

Eggs  and  young  larvae  described  by  Lutz  (1914)  of  an  unknown 
Brazilian  species  which  he  supposes  may  belong  to  the  tabanids, 
probably  belong  to  a leptid  species. 


PARASITES  OF  THE  EARLY  STAGES  OF  TABANID2E. 


Hymenopterous  Egg  Parasites;  Early  Discoveries. 

Koliar  (1854)  is  the  first  to  mention  an  egg  parasite  of  Tabanus. 
From  egg  masses  of  Tabanus  quatuornotatus  collected  at  Wippach, 
Austria,  by  Mann,  June  25,  1854,  there  were  observed  to  hatch  not 
only  young  Tabanus  larvas  but  “also  another  completely  developed 
insect  belonging  to  an  entirely  different  order  and  family,  a little 
animal  which  belongs  to  the  extraordinarily  large  and  still  inextric- 
able army  of  the  parasitic  wasps  (Ichneumonidae).”  It  was  con- 
cluded that,  immediately  after  the  Tabanus  had  deposited  its  eggs,  a 
parasitic  wasp  had  appeared  and  deposited  its  eggs  in  those  of  the 
Tabanus.  Parasitic  wasps  were  then  known  to  develop  in  the  eggs 
of  Lepidoptera,  chiefly  Bombycidae,  and  of  various  Hemiptera,  but  in 
Diptera  such  egg  parasites  had  not  been  observed  (Koliar).  The 
length  of  one  of  these  parasites  is  given  as  two- thirds  of  a line;  the 
size  of  the  Tabanus  eggs  as  one  line  in  length,  and  one-seventh  of  a 
line  in  diameter;  Koliar  thinks  it  probable  that  several  wasps  develop 
from  a single  Tabanus  egg,  which  is  probably  not  the  case.31 

On  egg  masses  of  a second  species  of  T abanus,  collected  by  himself 
at  Dornbach,  near  Vienna,  Koliar  found  a similar  but  specifically 
different  parasitic  wasp,  which  was  just  ovipositing  its  eggs  in  those 
of  the  Tabanus.  In  order  to  learn  how  much  time  was  necessary  for 
the  development  of  the  wasp,  Koliar  kept  the  Tabanus  eggs  in  a 
small  bottle  closed  by  means  of  perforated  paper,  and  obtained  on 
the  fifteenth  day  several  hundred  wasps.  From  the  number  of 
parasites  he  believed  he  was  justified  in  assuming  that  from  one 
Tabanus  egg  more  than  one  wasp  may  develop.  However,  the  num- 
ber of  eggs  in  the  cluster  had  been  said,  for  Tabanus  quatuornotatus 
Meig.  to  be  350  to  400,  and  it  is  not  said  whether  the  number  of 
wasps  hatching  exceeded  the  number  of  eggs. 

The  two  sexes  of  the  parasites  could  be  differentiated;  a description 
and  figures  were  promised  but  apparently  have  never  been  published. 

31  See  Hart  (1895),  Phanurus  tabanivorus,  p.  272. 

182 


WERNER  MARCHAND 


183 


Hart  (1895)  is  the  next  observer  who  noticed  the  egg  parasites  of 
Tabanidae.  Two  egg  masses  of  Tabanus  atratus  which  had  already 
produced  larvae  were  placed  in  a dry  vial,  and  a little  later  it  became 
evident  that  both  masses  had  been  parasitized  by  Hymenoptera, 
minute  black  imagos  emerging  freely  in  the  vial.  An  examination 
of  one  of  the  masses  showed  that  about  one-half  of  the  eggs  had  been 
infested.  Examples  of  the  imago  were  sent  to  Mr.  W.  H.  Ashmead, 
who  found  the  species  to  be  a new  one;  and  it  was  described  by  him 
as  Phanurus  tabanivorus  (Ashmead).  An  egg  of  the  Tabanus  is  fig- 
ured, containing  one  imago  of  the  parasite.32 

The  description  of  the  parasite  by  Ashmead  is  given  here: 

Phanurus  tabanivorus  (n.  sp.,  female). — “Polished  black,  impunctate,  the  head 
and  thorax  clothed  with  a fine  sparse  pubescence.  Head  subquadrate,  roundly 
emarginate  behind,  a little  wider  than  the  thorax;  eyes  oval,  faintly  pubescent; 
antennae  eleven-jointed,  black,  if  extended  backwards  not  quite  reaching  to  the 
apex  of  thorax,  and  terminating  in  a long  fusiform  five-jointed  club,  the  first 
joint  of  which  is  not  quite  as  wide  as  the  second;  ob-trapezoidal,  twice  as  wide 
as  long,  the  second,  third  and  fourth  joints  transverse  quadrate,  a little  wider 
than  long;  the  fifth  or  last  joint  conical  and  a little  narrower  than  the  preceding 
joint;  the  scape  is  about  as  long  as  the  funicle  with  the  pedicel,  the  latter  obconi- 
cal;  joints  of  funicle  a little  narrower  than  the  apex  of  the  pedicel,  the  first 
joint  scarcely  longer  than  thick,  the  second  and  third  small,  transverse 
moniliform.” 

“Thorax  subovoid,  not  twice  as  long  as  wide,  the  mesonotum  scarcely  longer 
than  wide,  the  scutellum  lunate,  polished,  without  pubescence;  wings  hyaline, 
ciliated,  the  cilia  on  the  anterior  and  posterior  margins  long,  much  shorter  at 
apical  margin;  tegulae  black;  venation  brown,  the  marginal  vein  a little  shorter 
than  the  stigmal,  the  latter  only  slightly  thickened  at  tip,  the  postmarginal  vein 
very  long,  fully  two  and  a half  times  as  long  as  the  stigmal;  legs  fuscous,  the 
trochanters,  knees,  tips  of  tibiae  and  tarsi  honey-yellow  or  testaceous.  Abdomen 
elongate,  pointed  fusiform,  about  twice  as  long  as  the  head  and  thorax  united, 
polished,  the  first  segment  not  longer  than  wide,  with  an  elevation  above  at  base, 
the  second  segment  the  longest,  twice  as  long  as  wide  at  apex,  the  suture  be- 
tween it  and  the  first  striated,  the  third  segment  hardly  half  as  long  as  the  second, 
the  fourth  about  two-thirds  the  length  of  the  third,  the  three  following  forming  a 
cone  of  which  the  fifth  is  very  short,  its  apical  margin  with  a median  sinus,  the 
sixth  twice  as  long  as  the  fifth,  the  seventh  very  short,  scarcely  discernible; 
sheaths  of  ovipositor  a little  prominent.” 


32  Ashmead’s  illustrations  (Figs.  55  and  56  of  his  paper)  have  been  omitted. 


184 


THE  EARLY  STAGES  OF  TABANIDiE 


“Male. — Length  0.8  mm.  Black,  but  with  the  head,  prosternum,  and  legs 
testaceous;  the  antennae  twelve-jointed,  brown-black,  with  all  the  joints  of  the 
flagellum,  except  the  pedicel  and  the  last  joint,  small,  moniliform,  joints  three  to 
five  increasing  in  size  but  smaller  than  pedicel,  joints  six  to  the  penultimate  a 
little  wider  than  long;  abdomen  not,  or  only  slightly,  longer  than  the  head  and 
thorax  united,  the  genitalia  long,  exserted,  curving  downwards.” 

“Habitat. — Havana,  Illinois.” 

“Types  in  collections  of  the  Illinois  State  Laboratory  of  Natural  History  and 
in  my  (Ashmead’s)  collection.” 

“Described  from  eleven  male  and  nine  female  specimens  bred  from  the  eggs  of  a 
common  horse-fly,  Tabanus  atratus  Fabr.” 

Hine  (1906)  also  has  observed  Phanurus  tabanivorus  and  reports 
that  he  reared  more  than  a hundred  specimens  from  a single  cluster 
of  eggs. 

Phanurus  tabani  Mayr. — In  his  monograph  of  the  N.  A.  Procto- 
trypidae,33  Ashmead  characterized  four  species  belonging  to  this 
gentis,  none  of  which,  however,  are  closely  allied  to  Phanurus  tabani- 
vorus. On  the  contrary,  it  appears  to  resemble  more  closely  three 
European  species  described  under  the  genus  Telenomus ; viz .,  Teleno- 
mus  othus  Hal.,  Telenomus  laricis  Hal.,  and  Telenomus  tabani  Mayr. 

Dr.  Gustav  Mayr,  “in  his  excellent  revision  of  the  European 
species  of  Telenomus ” did  not  recognize  the  validity  of  Thomson’s 
genus  Phanurus. 

Ashmead,  however,  believes  that,  as  defined  in  his  monograph,  the 
genus  can  be  readily  separated  from  Telenomus , although  both  Hali- 
day  and  Walker  have  described  Telenomi  which  should  now  be  rele- 
gated to  Phanurus;  while  Thomson,  in  his  definition  of  Telenomus , 
has  included  species  that  really  belong  to  the  genus  Hadronotus 
Forster. 

These  errors,  according  to  Ashmead,  probably  induced  Dr.  Mayr 
to  reject  the  validity  of  Phanurus  in  his  work  (cited  above). 

It  is  interesting  to  note  that  Phanurus  ( Telenomus ) tabani  Mayr 
has  habits  similar  to  Phanurus  tabanivorus , the  species  having  been 
bred  by  Brauer  from  a European  horse-fly,  Tabanus  sp. 

Phanurus  tabanivorus , although  evidently  related,  is  somewhat 
larger  in  the  female  sex,  smoother,  with  the  joints  of  the  antennae 

33  Ashmead,  N.  A.  Proctotrypidce , Monograph,  pp.  140  and  141. 


WERNER  MARCHAND 


185 


and  the  segments  of  the  abdomen  relatively  different,  while  the  male 
is  much  smaller,  differently  colored,  and  with  the  antennal  joints 
totally  dissimilar. 

Dr.  Mayr’s  species,  Phanurus  tabani,  approaches  nearest  to  Tele- 
nomus  lands  Hal.,34  with  which  he  makes  comparison;  while  Phanurus 
tabanivorus  agrees  more  nearly  with  Telenomus  othus  Hal.,  repre- 
sented on  the  same  plate,  Fig.  4 (Mayr’s  paper). 

Phanurus  emersoni  Girault. — A new  Phanurus  egg  parasite  of 
Tabanidae  was  discovered  by  Girault  quite  recently  (1916),  Phanurus 
emersoni  Girault,  and  was  reared  from  tabanid  eggs  at  Dallas,  Texas. 
Girault  gives  descriptions  of  three  allied  species. 

1.  Phanurus  opacus  Howard. — Both  sexes  are  black;  the  thorax 
above  is  subglabrous. 

2.  Phanurus  floridanus  Ashmead. — The  head  and  thorax  are  pol- 
ished, the  tibiae  and  knees  pale  brown;  segments  one  and  two  of 
abdomen  have  very  short  striae  at  base.  The  club  is  stouter  than 
in  ovivorus. 

3.  Phanurus  ovivorus  Ashmead. — The  club  is  slenderer  than  in  the 
preceding,  the  tibiae  dark,  the  thorax  above  showing  faint  reticulation, 
cephalad  but  mostly  glabrous.  The  first  two  segments  of  the  abdo- 
men do  not  have  striae  at  base,  or  else  these  are  extremely  minute  and 
short.  In  flavipes  the  vertex  and  scutellum  are  uniformly  finely 
reticulate.  The  species  ovivorus  is  very  close  to  opacus , if  not  identical 
with  it. 

4.  Phanurus  emersoni  Girault. — Female,  length  0.90  mm.  Black, 
the  wings  subhyaline,  the  venation  pale  dusky,  the  tarsi  yellow. 
It  differs  from  Phanurus  opacus  Howard  in  that  the  male  is  vari- 
colored in  the  latter,  and  from  the  female  opacus , floridanus , and 
ovivorus  in  that  the  vertex  and  scutum  of  the  latter  are  densely  reticu- 
lated. It  differs  from  tabanivorus  in  that  the  abdomen  of  the  latter 
is  only  somewhat  longer  than  the  rest  of  the  body,  the  third  segment 
is  not  a fourth  the  length  of  the  third  (second?),  the  thorax  above  is 
reticulated,  and  the  male  has  the  entire  thorax  honey-yellow,  also  the 
antennae  (besides  the  legs  and  head  as  in  tabanivorus ).  It  is  closely 
related  to  the  female  of  ovivorus , which  it  resembles.  The  stigmal 

34  Mayr,  Entomological  Magazine,  ii,  Plate  XIII,  Fig.  2. 


186 


THE  EARLY  STAGES  OF  TABANIDiE 


vein  is  nearly  twice  as  long  as  the  marginal,  and  about  half  the 
length  of  the  postmarginal.  Funicle  1 is  half  as  long  again  as  it 
is  wide,  two-thirds  the  length  of  the  pedicel,  No.  2 a little  shorter 
than  No.  1,  No.  3 still  shorter,  No.  4 globular,  smallest,  No.  5 cup- 
shaped, No.  6 the  same,  larger,  wider  than  long,  Nos.  7 and  8 sub- 
quadrate, No.  9 ovate,  longer  than  wide.  Short  distinct  striae  at 
base  of  segment  No.  2 of  the  abdomen. 

In  the  male,  Funicles  1 to  3 are  somewhat  longer  than  in  the  fe- 
male, while  Nos.  4 to  9 are  moniliform,  wider  than  long,  small;  the 
club  joint  is  ovate  and  as  long  as  Funicle  1 and  stouter. 

Described  from  a large  number  of  both  sexes  reared  from  tabanid 
eggs  at  Dallas,  Texas  (Bishop). 

Types. — Catalogue  No.  19,664,  U.  S.  N.  M.,  one  male,  eight  females, 
on  two  tags  and  a slide  bearing  one  male,  four  females. 

Types  of  opacus , ovivorus , jloridanus,  and  flavipes  examined. 

Telenomus  benefactor  Crawford. — Patton  and  Cragg  (1913),  (page 
298),  say  that  Telenomus  benefactor  Crawford  is  another  chalcid 
which  parasitizes  the  eggs  of  tabanids  in  the  Sudan. 

Telenomus  kingi  Crawford. — This  species  has  been  reared  from  eggs 
of  Tabanus  kingi. 

Unidentified  Parasites  Recorded. 

Chalcid  sp.  1.  King  (1910)  has  bred,  from  an  egg  mass  of  Tabanus 
tceniola , taken  at  Gebelein,  numbers  of  a small  Hymenopteron,  which, 
in  1910,  had  not  been  identified,  but  was  figured,  together  with  the 
parasitized  egg  mass,  showing  the  exit  hole  of  the  parasites.  As  the 
insects  are  figured  in  natural  size,  not  much  can  be  said  about  struc- 
tural details  (see  Plate  1,  Fig.  8,  and  text,  p.  170). 

Chalcid  sp.  2.  In  Madras,  a similar  insect,  which  has  not  been  iden- 
tified (Patton  and  Cragg,  1913),  regularly  destroys  large  numbers  of 
egg  masses  of  Tabanus  albimedius  and  Tabanus  striatus. 

A parasitized  egg  mass  can  be  recognized,  according  to  Patton  and 
Cragg,  by  the  almost  black  color  which  it  assumes  when  the  devel- 
opment of  the  embryos  of  the  Hymenopteron  is  almost  complete. 

Chalcid  sp.  3.  A hymenopterous  parasite  has  also  been  found  to 
infest  the  eggs  of  Goniops  chrysocoma  (McAtee).  Consequently  the 
phenomenon  seems  to  be  quite  general. 


WERNER  MARCHAND 


187 


Ichneumonid  sp.  An  unidentified  ichneumonid  parasite  of  an  uni- 
dentified Indian  species  of  Tabanus  is  figured  (Plate  5,  Fig.  76,  c)  by 
Maxwell-Leffroy  and  Howlett  (1909),  apparently  the  only  known 
instance  of  a true  ichneumonid  parasitic  in  Tabanidae.35 

Parasites  of  the  Larvce. 

On  parasites  of  the  larvae  we  possess  only  a few  remarks  by  Hart 
(1895),  who  found  a larva  covered  with  small  whitish  scales  which 
were  possibly  the  eggs  of  a parasite.  Nothing  further  is  known.36 

35  On  an  egg  mass  of  Tabanus  atratus  F.,  found  in  1915,  I noticed  a small 
Hymenopteron  which  I took  for  an  egg  parasite  and  which  I found  to  belong  to 
Tricho gramma.  However,  no  Tricho  gramma  hatched  from  the  egg  mass,  but 
instead  of  it,  a large  number  of  the  well  known  Phanurus,  apparently  tabanivorus 
Ashmead. 

36  To  these  should  be  added  the  author’s  own  observation  of  Nematode  para- 
sites which  were  repeatedly  found  in  larvae  of  Chrysops. 


DISCUSSION  OF  TABLE  II. 


Of  91  species  data  are  available;37  but  this  is  not  much  if  we  con- 
sider that  more  than  2,000  species  of  Tabanidae  have  been  described, 
and  76  species  have  been  recorded  for  the  State  of  New  Jersey  alone. 
Moreover,  in  a number  of  these  91  species  from  all  parts  of  the 
world,  we  have  only  very  fragmentary  data,  as  for  instance  in  the 
twelve  species  of  Chrysops  listed;  of  five  of  them  we  possess  only 
notes  on  their  oviposition;  the  whole  life  history  of  none  of  them  has 
been  worked  out.  There  are  also  comparatively  few  data  on  European 
species.38 

From  the  list  it  is  evident  that  the  majority  of  Tabanidae  of  which 
the  life  history  is  known,  are  aquatic  in  habitat:  of  91  species  noted, 
65  are  aquatic  or  probably  so,  18  are  terrestrial  or  probably  so;  of  8 
species  nothing  definite  can  be  said  about  their  habits.  The  terres- 
trial habit  is  then  to  be  considered  the  exception.  It  is  worthy  of 
note  that  all  the  known  species  of  Chrysops  are  aquatic,  in  as  far 
as  the  eggs  are  deposited  above  water,  or  the  larvae  have  been  found 
in  the  mud.  The  limit  between  an  aquatic  and  terrestrial  mode  of 
life  is,  of  course,  not  always  very  sharp  when  the  habitat  is  in  fact 
the  soft  mud  at  the  border  of  ponds,  brooks,  and  streams,  as  seems 
to  be  usually  the  case,  but  most  authors  agree  that  the  larvae  live  in 
mud  saturated  with  water,  an  environment  which  differs  physio- 
logically very  little  from  water  itself.  I have  therefore  listed  all 
species  as  aquatic  the  larvae  of  which  have  been  found  in  the  mud 
near  water,  or  where  the  eggs  are  deposited  above  water.  But  there 
is  no  doubt  that  some  tabanids  live  in  the  larval  condition  at  con- 

37  Of  two  or  three  of  the  91  species  discussed  here,  we  have  in  fact  only  in- 
dications about  their  breeding  habits,  no  actual  knowledge  of  the  stages,  so  in 
Gastr oxides,  Tabanus  fuscipes,  and  Tabanus  nigerrimus.  Leaving  these  out,  we 
still  have  about  88  species  on  which  some  data  are  available. 

38  Recently,  I have  obtained  larval  stages  of  9 other  North  American  species, 
bringing  the  total  number  of  species  on  which  data  are  known  close  to  100. 
These  species  are:  Chrysops  niger,  obsoletus , univittatus,  Tabanus  reinwardtii, 
pumilus , orion,  two  undetermined  species  of  Tabanus,  and  one  genus  incertum. 

188 


WERNER  MARCHAND 


189 


siderable  distance  from  water  and  probably  a greater  number  than  is 
apparent  from  this  table,  because  terrestrial  larvae  will  be  found 
much  more  rarely  being  less  accessible  and  spread  over  wider  areas. 
Since  the  genus  Tabanus  is  on  the  whole  phylogenetically  the 
younger,  in  comparison  with  Chrysops,  it  would  appear  that  in  some 
species  of  this  genus  the  larvae  have  become  secondarily  terrestrial,  a 
possibility  which  is  of  importance  for  the  understanding  of  the  group 
as  a whole.  This  may  also  apply  to  Hczmatopota,  a genus  absent 
in  Australia  and  apparently  of  more  recent  origin — while  retaining  a 
rather  primitive  wing-pattern — showing  aquatic  tendencies  in  the 
oviposition  of  some  species,  yet  in  its  common  and  widely  spread 
species,  Hcematopota  pluvialis,  completely  terrestrial  in  the  larval  and 
pupal  stages. 

Practically  nothing  is  known,  with  the  exception  of  the  few  in- 
stances listed,  of  the  early  stages  of  the  numerous  remaining  genera 
of  the  family  Tabanidae  other  than  Chrysops  and  Tabanus  proper, 
and  here  is  a splendid  opportunity  especially  for  workers  in  tropical 
countries. 

In  regard  to  continents,  the  data  in  our  possession  are  distributed 
as  follows: 


Africa 

North  America 

Europe 

Asia 

South  America 
Australia 


29  species. 

24  “ 

21  “ 

15  " (Two  identical  with  European;  viz.,  African 

species.) 

4 “ 

0 “ 


It  is  seen  that  Africa  ranges  highest,  and  concerning  this  particular 
subject,  has  ceased  to  be  a “dark  continent,”  as  compared  with 
North  America  or  Europe. 


Statistical  Table  of  Results  on  Early  Stages. 


190 


THE  EARLY  STAGES  OF  TABANID^ 


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NOTES  ON  METHODS  OF  REARING  AND  STUDYING  TABANIDS  IN 

EARLY  STAGES. 

Collecting  the  Larva. — The  natural  habitat  of  tabanid  larvae  is  the 
wet  mud  or  sand  in  the  immediate  neighborhood  of  water,  hence 
they  are  rarely  caught  by  the  usual  method  of  collecting  aquatic  in- 
sects by  means  of  a net.  The  lack  of  a practical  collecting  method  is 
probably  the  main  reason  why  these  animals  while  very  common 
have  passed  almost  unnoticed  in  an  epoch  of  fresh  water  biological 
investigations.  Neave  seems  to  have  employed  large  nets,  as  did 
Hart  also,  but  Neave  was  able  to  send  out  a collecting  staff  of  ne- 
groes to  obtain  his  material.  The  use  of  an  ordinary  sieve,  first  ap- 
plied by  Hine  to  collect  the  larvae  of  Tabanus  vivax  in  rapid  streams, 
is  more  advisable  for  collecting  the  larvae  from  the  mud.  Patton 
and  Cragg  suggest  placing  lumps  of  mud  and  sand  with  water  in  a 
pail;  by  stirring  the  mass  the  large  larvae  appear  floating  at  the  sur- 
face. The  smaller  ones  are  caught  when  the  muddy  water  is  passed 
through  a sieve. 

Rearing  Vessels. — The  methods  of  various  authors  in  rearing  taba- 
nid larvae  have  been  treated  in  connection  with  the  species.  Thus  in 
the  paragraphs  on  Tabanus  lasiophthalmus  and  vivax,  details  of  Hine’s 
method  in  rearing  these  species  are  found,  and  Mitzmain’s  valuable 
contributions  to  breeding  technique  are  found  under  Tabanus  striatus. 

Hine  proposes  to  keep  the  larvae  in  jelly  glasses  the  covers  of  which 
are  perforated  by  a few  holes,  and  which  are  half  filled  with  wet 
sand.  Mitzmain  uses  dishes  with  some  mud  and  wet  filter  paper. 

Patton  and  Cragg  have  advised  the  use  of  very  large  trays,  several 
feet  long  and  six  inches  high,  in  which  large  numbers  of  larvae  may 
be  reared  under  almost  natural  conditions.  The  bottom  of  the  tray 
has  to  have  a hole  closed  by  a cork  stopper,  to  make  it  possible  to 
change  the  water  in  the  tray  from  time  to  time.  Pupae  should  be 
taken  out,  as  the  larvae  may  injure  them,  and  placed  in  separate 
cages,  in  little  vertical  holes.  Near  each  pupa  a little  flag  is  fastened, 
bearing  the  number  of  the  pupa,  or  other  data. 

196 


WERNER  MARCHAND 


197 


Neave,  who  was  raising  many  different  tabanid  species  in  southern 
Nyasaland,  found  that  the  best  receptacles  which  he  could  obtain 
locally  were  the  small  basin-shaped  vessels  made  of  hard  clay  by  the 
natives.  These  were  of  various  sizes,  from  six  inches  to  a foot  in 
diameter.  They  were  placed  separately  under  cages  made  of  mos- 
quito netting  on  a wood  framework.  Neave  recovered  the  larvae 
for  examination  or  other  purposes  merely  by  washing  them  out  of 
the  mud  or  salid  in  which  they  were  placed.  This  of  course  requires 
great  care  in  the  case  of  the  smaller  species.39 

Feeding. — While  most  authors  give  earthworms  as  food  to  the  larger 
larvae,  Neave  advises  the  use  of  immature  larvae  of  muscid  flies, 
collected  from  the  carcasses  of  rats,  etc.,  trapped  for  the  purpose. 
These  larvae  buried  themselves  at  once  in  the  mud,  where  they  were 
apparently  consumed  by  the  tabanid  larvae,  which  thrived  under  these 
conditions.  The  larger  species  also  greedily  attacked  the  freshly 
killed  bodies  of  small  tadpoles,  mollusks,  and  bits  of  fish,  placed  on  the 
surface  of  the  mud,  though  they  were  seldom  actually  seen  to  do 
this  unless  examined  at  night.  It  was  found  in  most  cases  that  the 
tabanid  larvae  did  best  in  mud  or  sand,  this  point  being  usually  de- 
cided by  the  conditions  under  which  they  had  been  found,  which  was 
very  wet,  but  without  standing  water  on  the  surface. 

Transportation. — If  it  is  necessary  to  transport  for  any  distance 
larvae  which  have  not  reached  the  resting  stage,  it  is  important  that 
the  jars,  etc.,  in  which  they  are  placed  should  contain  only  wet  mud 
or  sand  and  that  there  should  be  no  standing  water  on  the  surface. 
Some  of  Neave’s  earliest  captures,  which  had  to  be  transported  50 
or  60  miles  from  the  Shire  River  to  Mlanje,  were  nearly  all  lost  from 
this  cause,  the  larvae  being  apparently  drowned  by  the  movements 
of  the  water  on  the  surface. 

Treatment  of  Pupal  Stages. — Neave  found  that  the  soil  in  which  the 
pupae  are  kept  should  be  considerably  drier  than  that  which  suits 
the  larvae. 

Patton  and  Cragg  have  proposed  to  remove  the  fresh  pupae  from 
the  vessels  in  which  the  larvae  are  kept  and  to  place  them  vertically 

39  For  rearing  tabanid  larvae  in  test-tubes,  see  Marchand,  J.  Econ.  Entomol., 
1917,  x,  469-72. 


198 


THE  EARLY  STAGES  OF  TABANED^E 


in  open  holes  in  sand,  where  they  wriggle  themselves  soon  into  the 
desired  position.  Each  pupa  receives  a label  in  the  form  of  a little 
flag  which  is  fastened  in  the  sand.  As  soon  as  a pupa  has  hatched,  it 
is  taken  out  with  its  label. 

According  to  Neave,  it  is  difficult  to  obtain  good  specimens  from 
bred  material,  as  the  imagos  begin  to  fly  about  and  to  injure  them- 
selves before  they  are  hard  enough  to  be  killed.  They  should  there- 
fore be  placed  in  larger  cages  and  kept  there  until  they  are  sufficiently 
hardened. 

Points  Important  in  Description. — Specific  differences  in  tabanid 
larvae  are  not  always  easy  to  detect,  especially  in  those  of  Hcemato- 
pota.  They  are  generally  found,  according  to  Neave,  in  the  distri- 
bution of  the  pigmented  areas  on  the  last  segment  around  the  base 
of  the  syphon  and  the  anus.  These  so  called  pigmented  areas  are 
really  areas  of  pigmented  hairs  (Waterston)  in  which  are  entangled 
small  foreign  bodies.  Their  actual  color  therefore  varies  to  some 
extent  with  that  of  the  medium  in  which  the  larvae  have  lived.  The 
amount  of  pigmentation,  though  not  its  distribution,  also  varies  with 
the  age  of  the  larvae. 

Hart  considers  the  striation  of  the  lateral  areas  of  the  prothorax  of 
great  systematic  importance  in  the  description  of  the  larvae. 

For  practical  purposes  of  description  the  following  points  should 
be  noted  (Patton  and  Cragg):  In  the  larvae,  abdominal  markings, 
presence  or  absence  of  striae,40  characteristics  of  the  pseudopods 
(prolegs),  length  of  the  syphon  tube,  and  structure  of  the  antennae. 
In  the  pupae,  length  of  the  antennal  sheath,  character  of  the  thoracic 
spiracle,  particularly  its  inner  margin,  length  of  the  hairs  on  the 
abdomen,  structure  of  the  abdominal  spiracles,  and  shape  and  size 
of  the  spines  and  teeth  on  the  eighth  segment. 

Mr.  James  Waterston,  of  the  Imperial  British  Bureau  of  Ento- 
mology, is  quoted  by  Neave  as  having  suggested  the  convenient 
name  “ aster”  for  the  group  of  hooks  at  the  termination  of  the  last 
segment  of  the  pupa.  The  form  of  this  differs  a good  deal  in  the 
various  species,  and  another  characteristic  which  seems  of  some 
specific  value  is  the  nature  of  the  uppermost  section,  often  isolated, 

40  Especially  on  the  thoracic  segments. 


WERNER  MARCHAND 


199 


of  the  series  of  combs  on  the  anterior  part  of  the  last  segment;  this  is 
called  by  Neave  the  dorsolateral  comb.  It  is  not  always  present 
and  varies  much  in  form. 

Preserving. — To  preserve  the  larvae  and  pupae,  for  purposes  of  dis- 
section, etc.,  our  methods  are  still  undeveloped.  Hart41  (1895)  says: 
“The  best  results  with  most  larvae  of  any  size  were  obtained  by 
heating  them  in  water,  not  too  rapidly,  to  about  200°  F.,  and  setting 
them  aside  till  cool.  A small  percentage  of  acetic  acid  will  prevent 
the  collapsing  of  very  soft  larvae.”  The  principal  trouble  with  this 
method  arises  from  the  expansion  of  the  air  within,  but  a slight  infla- 
tion is  sometimes  desirable.  This  method  is  not  suitable  for  pupae 
generally,  and  Hart  advises  the  use  of  80  per  cent  alcohol  and  water 
for  their  preservation.  Experiments  with  formalin  indicate  that  it 
will  satisfactorily  preserve  small  and  easily  penetrable  forms. 

Malloch  (1917)  has  given  further  methods  for  preserving  the  larvae 
and  pupae. 


41  Hart  (1895).  pp.  159  and  160. 


BIBLIOGRAPHY.* 


Ashmead,  W.  H.,  Descriptions  of  three  new  parasitic  Hymenoptera  from  the 
Illinois  River.  Phanurus  tabanivorus,  Bull.  Illinois  State  Lab.  Nat.  Hist., 
1895-96,  iv,  274-276.  (See  Hart  (1895).) 

Bainbridge,  T.,  and  Fletcher,  Some  South-Indian  Insects,  Madras,  1914. 

Baldrey,  F.  S.  H.,  The  evolution  of  Trypanosoma  evansi  through  the  fly:  Tabanus 
and  Stomoxys,  J.  Trop.  Vet.  Sc.,  1911-12,  vi-vii,  271-282. 

Beling,  T.,  Beitrag  zur  Metamorphose  der  zweifluegeligen  Insecten,  Arch. 
Naturges.,  1875,  xli,  35-39. 

Beling,  Beitrag  zur  Metamorphose  zweifliigeliger  Insecten  aus  den  Familien 
Tabanidae,  Leptidae,  Asilidae,  Empidae,  Dolichopodidae,  and  Syrphidae,  Arch. 
Naturges.,  1882,  xlviii,  187-240;  C.  relictus,  pp.  187-190. 

Bodkin,  G.  E.,  and  Cleare,  L.  D.,  Notes  on  some  animal  parasites  in  British 
Guiana,  Bull.  Entomol.  Research,  1916,  vii,  179-190. 

Brauer,  F.,  Beobachtung  Marno’s  liber  Hexatoma , Verhandl.  zool.  bot.  Ges.,  1868, 
xviii,  74-75. 

Brauer,  Kurze  Characteristik  der  Dipteren-Larven,  Verhandl.  zool.  bot.  Ges., 
1869,  xix,  448. 

Brauer,  Beitrag  zur  Verwandlungsgeschichte  der  Regenbreme  ( Hcematopota 
pluvialis  L.),  Verhandl.  zool.  bot.  Ges.,  1869,  xix,  921-922. 

Brauer,  Die  Zweifliigler  des  Kaiserlichen  Museums  zu  Wien.  III.  Die  Tabanus- 
Arten  der  europaeischen,  mediterranen  und  sibirischen  Subregionen,  Denkschr. 
kaiser.  Akad.  Wissensch.,  Mathem.  Naturw.  Classe,  1880,  xlii,  151  (pupa 
of  Tabanus  solstitialis) . 

Brauer,  Die  Zweifliigler  des  Kaiserlichen  Museums  zu  Wien.  HI,  1883,  p.  24, 
Tabanidae.  (Contains  description  of  larva  of  Hexatoma  pellucens,  illustra- 
tions of  the  latter  and  of  larvae  of  T abanus  spodopterus  and  cordiger.) 

Brimley,  C.  S.,  Notes  on  the  life-histories  of  Tabanidae  (Diptera),  Entomol.  News , 
1909,  xxii,  133. 

Brumpt,  E.,  Precis  de  parasitologie,  Paris,  1910. 

Degeer,  C.,  Memoires  pour  servir  a l’histoire  des  insectes,  1752-58,  7 vols. 

Degeer,  Bromsarnas  ursprung,  uptaeckt  af  Carl  Degeer,  Konigl.  Vetenskaps 
Academiens  Handlinger  for  Ar  1760,  xxi,  276-291,  Plate  IX,  Figs.  1,  2, 
3,  and  4.  (The  illustrations  of  Tabanus  bovinus  are  identical  with  those 
given  in  the  Memoires,  but  the  illustration  of  the  pupa  is  more  exactly  re- 
produced in  the  Memoires.) 

Degeer,  Memoires  pour  servir  a Phistoire  des  insectes,  1776,  vi,  5th  Memoire. 
German  edition  (Goeze),  1882. 

Dufour,  L.,  Notices  entomologiques.  I.  Consultation  sur  une  larve  aquatique, 
Ann.  Soc.  entomol.  France,  1862,  Plate  II,  Fig.  2,  a and  b. 


* Reference  is  made  to  the  larval  stages  of  Tabanidae  in  a number  of  text- 
books or  other  papers  all  of  which  were  not  mentioned  in  this  Bibliography  if 
they  contained  no  original  information. 

200 


WERNER  MARCHAND 


201 


Fabricius,  J.  C.,  Entomologia  Systematica,  4 vols.,  Hafniae,  1772-94;  Supple- 
ment 1798. 

von  Friedenfels,  E.,  Ueber  Artemia  salina  und  andere  Bewohner  der  Soolen- 
teiche  in  Salzburg,  Verhandl.  Mitt.  Siebenbiirg.  Vereins  fiir  Naturwissen- 
schaften  in  Herrmannstadt,  1880,  xxx,  112-178  (p.  168  Tabanus  autumnalis) . 

Girault,  A.,  A new  Phanurus  from  the  United  States,  with  notes  on  allied  species, 
Canad.  Entomologist,  1916,  xlviii,  149-150. 

Goldi,  E.  A.,  Die  sanitarisch-pathologische  Bedeutung  der  Insekten  und  ver- 
wandten  Gliedertiere,  namentlich  als  Krankheits-Erreger  und  Krankheits- 
Ubertrager,  Berlin,  1913. 

Graber,  V.,  Ueber  neue  otocystenartige  Sinnesorgane  der  Insecten  (Neues  Organ 
einer  Fliegenmade),  Arch,  mikroskop.  Anat.,  1878,  xvi. 

Graber,  Die  chordotonalen  Sinesorgane  und  das  Gehor  der  Insekten,  Arch, 
mikroskop.  Anat.,  1882-83,  xx,  xxi. 

Griinberg,  K.,  Die  blutsaugenden  Dipteren,  Jena,  1907. 

del  Guercio,  Le  tipuli  ed  i tafani  nocivi  nelle  risaie  de  Molinella  (Bologna),  Redia, 
1913,  299-345. 

Hart,  C.  A.,  On  the  entomology  of  the  Illinois  River  and  adjacent  waters,  Bull. 
Illinois  State  Lab.  Nat.  Hist .,  1895-96,  iv,  220-247.  (Gives  photographic 
pictures  of  the  larvae.  Same  volume  contains  original  description  of 
Phanurus  tabanivorus  Ashmead.) 

Henneguy,  L.  F.,  Les  insectes,  Paris,  1904.  (Graber’s  organ,  p.  488.) 

Herms,  W.  B.,  Medical  and  veterinary  entomology.  A textbook  for  use  in 
schools  and  colleges  as  well  as  a handbook  for  the  use  of  physicians, 
veterinarians  and  public  health  officials,  New  York,  1915. 

Hine,  J.  S.,  On  the  life  history  of  Tabanus  vivax,  Ohio  Naturalist,  1903,  iv,  1-2. 

Hine,  Tabanidae  of  Ohio,  Ohio  State  Univ.  Contribution  from  the  Dept,  of 
Zool.  and  Entomol.,  Ohio  Acad.  Sc.,  No.  10,  Special  papers,  No.  5,  1903. 

Hine,  Insects  injurious  to  stock  in  the  vicinity  of  the  Gulf  Biologic  Station, 
U.  S.  Dept.  Agric.,  Division  of  Entomol.,  Bull.  44,  1904,  57-60.  (Mentions 
eggs  of  T.  costalis.) 

Hine,  Same  paper  reprinted  in  Second  Rep.  Gulf  Biol.  Station,  1903,  Bull.  2,  1904. 

Hine,  Some  economic  considerations  with  reference  to  the  Tabanidae,  Proc. 
XVIth  Annual  Meeting  Assn.  Economic  Entomologists,  U.  S.  D.  A.  E., 
No.  46,  1904,  23-25;  Gulf.  Biol.  Station  Rep.,  Bull.  2,  1904,  86-87,  mentions 
eggs  of  trimaculatus. 

Hine,  Habits  and  life  histories  of  some  flies  of  the  family  Tabanidae,  U.  S.  Dept. 
Agric.,  Bureau  Entomol .,  Technical  Series  12,  1906,  pt.  2,  19-38. 

Howard,  L.  O.,  The  insect  book,  1901.  (The  family  Tabanidae  is  treated  on 
pages  131-133.  Riley’s  figures  of  Tabanus  atratus  are  reproduced.) 

Keilin,  D.,  Sur  certains  organes  sensitifs  constants  chez  les  larves  de  Dipteres 
et  leur  signification  probable,  Compt.  rend.  Acad.,  1911,  cliii,  977-979. 
Quoted  in  Brauer  (1883).  No  tabanids  mentioned. 

King,  H.  H.,  Report  on  economical  entomology,  Rep.  Wellcome  Research  Lab. 
Gordon  Memorial  College,  1908,  iii,  212-214.  (Life  history  of  Tabanus 
biguttatus.) 


202 


THE  EARLY  STAGES  OF  TABANID^E 


King,  Third  Rep.  Wellcome  Research  Lab.  Gordon  Memorial  College,  and  Bull. 
Entomol.  Research,  1910,  i,  pt.  2.  (Bionomics  of  Tabanus  par  and  tceniola.) 

King,  Some  observations  on  the  bionomics  of  Tabanus  ditceniatus  Macquart, 
and  Tabanus  kingi  Austen,  Bull.  Entomol.  Research,  1910,  i,  pt.  4. 

Kollar,  M.  V.,  Beitrag  zum  Haushalte  der  sehr  lastigen  Viehbremsen  (Tabanidae), 
Sitzungsb.  math,  naturwissensch.,  Classe  d.  k.  Acad.  Wissensch,  1854,  xiii, 
531-535. 

Krauss,  H.,  Otocystenartiges  Organ  bei  Tabanus  autumnalis  L.,  Zool.  Anz., 
Carus,  1879,  ii,  229-230. 

Lecaillon,  A.,  Sur  la  ponte  des  ceufs  et  la  vie  larvaire  des  Tabanides,  particu- 
lierment  du  Taon  a quatre  taches  ( Tabanus  quatuornotatus  Meig.),  Ann. 
Soc.  entomol.  France,  1905. 

Lecaillon,  Sur  l’organe  de  Graber  de  la  larve  de  Tabanus  quatuornotatus  Meig., 
Compt.  rend.  Assn,  anat.,  1905,  vii,  130-131,  3 figs. 

Lecaillon,  Sur  quelques  points  de  l’histoire  naturelle  des  tabanides,  en  particulier 
de  Tabanus  quatuornotatus  Meig.,  Compt.  rend.  Soc.  biol.,  1906,  lx,  459. 

Lecaillon,  Deuxieme  note  sur  l’organe  de  Graber,  Compt.  rend.  Assn,  anat.,  1906, 
viii,  65-67. 

Lecaillon,  Sur  la  structure  de  la  couche  chitineuse  tegumentaire  et  sur  les  in- 
sertions musculaires  de  las  larve  de  Tabanus  quatuornotatus  Meigen,  Compt. 
rend.  Assn,  anat.,  1906,  viii,  68-70. 

Lecaillon,  Nouvelles  observations  sur  la  ponte  des  oeufs  et  la  vie  larvaire  du 
Tabanus  quatuornotatus  Meig.  (Dipt.),  Ann.  Soc.  entomol.  France,  1911,  lxxx. 

Lutz,  A.,  Dipteren.  Mem.  Inst.  Oswaldo  Cruz,  Rio  de  Janeiro,  1914,  vi,  43-49. 

Macquart,  Histoire  naturelle  des  insectes.  Dipteres,  1834,  i,  193.  (Degeer’s 
figure  reproduced.) 

Malloch,  J.  R.,  A preliminary  classification  of  Diptera,  exclusive  of  Pupipara, 
based  upon  larval  and  pupal  characters,  with  keys  to  imagines  in  certain 
families.  Bull.  Illinois  State  Lab.  Nat.  Hist.,  1917,  xii,  pt.  1. 

Marno,  E.,  Zur  Biologie  von  Hexatoma,  Verhandl.  zool.  bot.  Ges.,  1868,  xviii,  74-75. 

Maxwell-Leffroy,  H.,  and  Howlett,  F.  M.,  Indian  insect  life,  Agric.  Research 
Inst.,  Pusa,  India,  Calcutta,  and  London,  1909.  (Tabanidae,  pp.  592-595; 
Tabanus  striatus,  etc.;  larval  habits  of  Gastr oxides  ater.) 

McAtee,  W.  L.,  Facts  in  the  life  history  of  Goniops  chrysocoma  (Diptera,  Tabani- 
dae), Proc.  Entomol.  Soc.  Washington , 1911,  xiii,  21-29. 

Mitzmain,  M.  B.,  The  biology  of  Tabanus  striatus  Fabricius,  the  horsefly  of  the 
Philippines,  Phil.  J.  Sc.,  Section  B,  1913,  viii,  197-221,  Plate  7. 

Neave,  S.  A.,  The  Tabanidae  of  southern  Nyasaland,  with  notes  on  their  life 
histories,  Bull.  Entomol.  Research,  1915,  v,  pt.  4,  287-320,  4 plates. 

Osburn,  R.  C.,  Tabanidae  as  inhabitants  of  the  Hydrophytic  Area,  J.  New  York 
Entomol.  Soc.,  1913,  xxi,  63-65. 

Packard,  A.  S.  Textbook  on  entomology,  New  York,  1898,  gives  on  page  627, 
Fig.  520,  an  illustration  of  the  pupa  of  Midas  clavatus  which  is  erroneously 
referred  to  Tabanus  atratus.  Fig.  520  c probably  represents  atratus  (after 
Riley?,  very  imperfect),  520  d is  Proctacanthus.  The  pupa  of  Tabanus 
lineola  is  represented  on  p.  630,  Fig.  585. 


WERNER  MARCHAND 


203 


Paoli,  G.,  Intorno  all’  organo  del  Graber,  nelle  larvae  di  ditteri  tabanidi,  Redia, 
1907,  iv,  247-258. 

Patton,  W.  S.,  and  Cragg,  F.  W.,  Textbook  of  medical  entomology,  Christian 
Literature  Society  for  India,  London,  Madras,  and  Calcutta,  1913. 

Perris,  E.,  Histoire  des  insectes  du  pin  maritine,  Ann.  Soc.  Entomol.  France , 
1870,  x,  135-232.  (Description  of  larva  of  Hcematopota,  pp.  196-198;  pupa, 
pp.  198-199;  tabanid  early  stages  in  general,  pp.  199-201.) 

Picard,  F.,  and  le  Blanc,  G.  R.,  Sur  les  moeurs  lignicoles  de  la  larve  de  Tabanus 
cordiger  Meig.  (Dipt.  Tabanidae),  Bull.  Soc.  Entomol.  France , 1913,  318-321, 
Fig.  1. 

Portschinsky,  Biologie,  Beschreibung,  Bekampfung  von  Tabaniden,  (Russ),  4th 
edition,  Trd.  B.  entom.  Ucen.  Kom.  M.  Zeml.,  St.  Petersburg.  (Travaux  de 
Bureau  entomologique  de  Comite  scientifique  du  Ministere  d ’Agriculture  et 
des  Domaines.  St.  Petersbourg,  Russe),  1908,  i,  1-52,  21  figs.  (This  paper 
contains  an  illustration  of  the  egg  mass  of  the  European  species  Tabanus 
montanus  which  is  black  and  placed  on  the  leaf  of  a grass  plant  above 
water,  and  two  illustrations  of  the  pupa  of  Tabanus  tarandinus.  These 
two  species  have  to  be  added  to  the  list  of  species  on  which  data  are 
available.  The  illustrations  are  not  reproduced  because  the  paper  which 
I have  seen  on  one  occasion,  became  unavailable.) 

Riley,  C.  V.,  The  black  breeze-fly — Tabanus  atratus  Fabr.,  Second  Ann.  Rep.  on 
the  noxious,  beneficial,  and  other  insects  of  the  State  of  Missouri,  made 
to  the  State  Board  of  Agriculture,  1870,  128-132. 

Riley,  W.  A.,  and  Johannsen,  O.  A.,  Handbook  of  medical  entomology,  Ithaca, 
1915,  (gives  illustrations  of  the  larva  of  Tabanus  atratus  and  of  eggs  of  a 
common  unknown  species). 

Scholtz,  H.,  Ueber  den  Aufenthalt  der  Dipteren  wahrend  ihrer  ersten  Stande, 
Z.  Entomol.,  1848,  25-34.  (p.  28,  tabanid  larvae.) 

Sharp,  D.,  The  Cambridge  Natural  History,  Insects,  1901,  vi,  pt.  2,  483. 
( Tabanus  larva,  supposed  to  be  that  of  Atylotus  fulvus) . 

Surcouf,  J.  M.  R.,  and  Ricardo,  G.,  Etude  Monographique  des  Tabanides 
d’Afrique  (Groupe  des  Tabanus),  Paris,  1909  (Pupa  of  Tabanus  bromius , 
etc.).  These  figures  reproduced  in  Brumpt  (1910). 

Wahlberg,  P.  F.,  Bidrag  till  Svenska  Dipternas  Kannedom.  Koningl.  Wetenskaps 
Academiens  Handlingar,  for  ar  1838,  Stockholm,  1839.  (Though  Tabanus 
glaucopis  imago  is  described,  nothing  is  said  about  the  larval  stage.)  Quoted 
by  Brauer  (1883). 

Walsh,  B.  D.,  On  certain  remarkable  or  exceptional  larvae,  coleopterous,  lepid- 
opterous,  and  dipterous,  with  demonstrations  of  several  species  injurious 
to  vegetation  which  have  been  already  published  by  Agricultural  Journals, 
Proc.  Boston  Soc.  Nat.  Hist.,  1863,  ix,  302-306. 

Walton,  W.  R.,  Notes  on  the  egg  and  larva  of  Goniops  chrysocoma  O.  S.,  Entomol. 
News,  1908,  xix,  464-465. 

Westwood,  J.  O.,  Introduction  to  the  modern  classification  of  insects,  1840,  ii, 
538. 

Zetterstedt,  Diptera  Scandinaviae,  i,  105  ( Tabanus  larvae),  and  123  ( Chrysops ). 


Plate  1. 


Fig.  1.  Female  of  Chrysops  mcerens , ovipositing  on  Typha  leaf.  After  Hine 
(photograph  from  life). 

Fig.  2.  Egg  masses  of  Chrysops  mcerens , on  Sparganium  leaf.  After  Hine 
(photograph) . 

Fig.  3.  Egg  mass  of  Tabanus  stygius  on  Sagittaria  leaf.  After  Hine. 

Fig.  4.  Egg  mass  of  Tabanus  stygius  on  Peltandra  leaf.  After  Hine. 

Fig.  5.  Egg  mass  of  Tabanus  stygius  in  unusual  location.  After  Hine. 

Fig.  6.  Egg  masses  of  Tabanus  sp.}  After  Riley  and  Johannsen  (photograph). 

Fig.  7.  Egg  mass  of  Tabanus  sp.?  Natural  size  24  mm.  After  Maxwell- 
Leffroy  and  Howlett  (colored  original  yellow). 

Fig.  8.  Egg  mass  of  Tabanus  tceniola , with  chalcid  parasites.  After  King 
(colored  plate) . 

Fig.  9.  a,  Egg  mass  of  Tabanus  tceniola ; b , young  larva.  After  King 
(colored  plate). 

Fig.  10.  Egg  mass  of  Tabanus  par.  After  King  (colored  plate). 

Fig.  11.  Young  larva  of  Tabanus  par.  Natural  size  10  mm.  After  King 
(colored  plate). 

Fig.  12.  Egg  mass  of  Tabanus  bicallosus  on  a blade  of  grass.  After  Patton 
and  Cragg. 

Fig.  13.  Two  single  eggs  of  Tabanus  bicallosus.  After  Patton  and  Cragg. 

Fig.  14.  Egg  mass  of  Chrysops  dispar,  on  a blade  of  grass.  After  Patton  and 
Cragg. 

Fig.  15.  Single  egg  of  Chrysops  dispar.  After  Patton  and  Cragg. 

Fig.  16.  Egg  mass  of  Tabanus  virgo,  on  a dry  twig.  After  Patton  and  Cragg. 

Fig.  17.  Single  egg  of  Tabanus  ditceniatus.  After  Patton  and  Cragg. 

Fig.  18.  Egg  mass  of  Tabanus  biguttatus.  Natural  size  14  mm.  After  King 
(colored  plate) . 

Fig.  19.  Egg  mass  of  Tabanus  speciosus.  After  Patton  and  Cragg. 

Fig.  20.  Egg  mass  of  Tabanus  kingi.  After  King. 

King’s  illustration  of  a rock  situated  above  water,  showing  the  location  of 
these  egg  masses,  has  been  omitted. 


MONOGRAPH  NO.  13. 


PLATE  1. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  2. 


Fig.  21.  Egg  mass  of  Tabanus  ditceniatus  spread  out  in  a single  layer  on  a 
blade  of  grass.  After  Patton  and  Cragg. 

Fig.  22.  Egg  mass  of  Tabanus  striatus  on  paddy  leaf.  Natural  size  13  mm. 
After  Bainbridge  and  Fletcher. 

Fig.  23.  Same  egg  mass,  magnified.  After  Bainbridge  and  Fletcher. 

Fig.  24.  Female  of  Tabanus  striatus , ovipositing.  Natural  size  of  fly  19  mm. 
After  Mitzmain  (photograph). 

Fig.  25.  Egg  masses  of  Tabanus  striatus.  After  Mitzmain  (photograph). 

Fig.  26.  Empty  (?)  egg  mass  of  Tabanus  striatus.  After  Mitzmain  (photo- 
graph). 

Fig.  27.  Egg  mass  of  Tabanus  striatus  in  process  of  hatching.  After  Mitz- 
main (photograph). 

Fig.  28.  Female  of  Goniops  chrysocoma,  ovipositing.  After  McAtee  (photo- 
graph). 

Fig.  29.  Egg  mass  of  Goniops  chrysocoma,  seen  from  above.  After  Walton. 

Fig.  30.  Egg  mass  of  Goniops  chrysocoma,  lateral  view.  After  McAtee  (pho- 
tograph) . 

Fig.  31.  Egg  mass  of  Goniops  chrysocoma.  Natural  size  14  mm.  After  Mc- 
Atee (photograph). 

Fig.  32.  Empty  egg  mass  of  Goniops  chrysocoma  after  hatching.  After 
McAtee. 

Fig.  33.  Double  egg  mass  of  Tabanus  quatuornotatus.  After  Lecaillon. 

Fig.  34.  Two  single  egg  masses  of  Tabanus  quatuornotatus.  Natural  size  9 
mm.  After  Lecaillon. 

Fig.  35.  Group  of  egg  masses  of  Tabanus  quatuornotatus  on  dried  twig.  After 
Lecaillon. 

Figs.  36,  37,  and  38.  Egg  masses  of  Tabanus  quatuornotatus,  magnified.  After 
Lecaillon. 


MONOGRAPH  NO.  13. 


PLATE  2. 


(Marchand:  The  early  stages  of  Tabanidse.) 


Plate  3. 


Fig.  39.  Larva  of  Chrysops  vittatus.  Natural  size  15  mm.  After  Hart  (pho- 
tograph) . 

Fig.  40.  Larva  of  Tabanus  stygius.  Natural  size  52  mm.  After  Hart  (pho- 
tograph) . 

Fig.  41.  Larva  of  Tabanus  atratus.  Natural  size  53  mm.  After  Hart  (pho- 
tograph) . 

Fig.  42.  Larva  of  Tabanus  sp.?  Natural  size  24  mm.  After  Hart  (photo- 
graph). 

Fig.  43.  Larva  of  Tabanus  vivax.  Natural  size  36  mm.  After  Hine. 

Fig.  44.  Larva  of  Tabanus  lasiophthalmus.  Natural  size  23  mm.  After 
Hine. 

Fig.  45.  Larva  of  Tabanus  atratus.  After  W.  A.  Riley  and  Johannsen  (pho- 
tograph) . 

Fig.  46.  Larva  of  Tabanus  atratus.  Natural  size  52  mm.  After  C.  V.  Riley. 

Fig.  47.  Larva  of  Tabanus  ditceniatus.  Lateral  view  of  immature  larva. 
After  King  (colored  plate). 

Fig.  48.  Larva  of  Tabanus  par,  almost  full  grown.  Natural  size  52  mm. 
After  King  (colored  plate). 

Fig.  49.  Larva,  full  grown,  of  Tabanus  tceniola.  After  King  (colored  plate). 

Fig.  50.  Larva  of  Chrysops  wellmani.  Natural  size  13  mm.  After  Neave 
(Terzi). 

Fig.  51.  Larva  of  Tabanus  gratus.  Natural  size  23  mm.  After  Neave 
(Terzi). 

Fig.  52.  Larva  of  Tabanus  atrimanus.  Natural  size  32  mm.  After  Neave 
(Terzi). 

Fig.  53.  Larva  of  Tabanus  insignis.  Natural  size  34  mm.  After  Neave 
(Terzi). 

Fig.  54.  Larva  (supposed  larva)  of  Tabanus  pertinens.  Natural  size  36  mm. 
After  Neave  (Terzi). 


MONOGRAPH  NO.  13. 


PLATE  3. 


44 


(Marchand : The  early  stages  of  Tabanidae.) 


Plate  4. 


Fig.  55.  Larva  of  Tabcmus  sp .?  a , Ventral  view;  cross-section  of  segment; 
c,  dorsal  view.  Natural  size  32  mm.  After  Brumpt. 

Fig.  56.  Larva  of  Tabanus  kingi.  After  King. 

Fig.  57.  Larva  of  Tabanus  ditceniatus.  a,  Immature  larva;  b,  mature  larva, 
lateral  view;  c,  6th  and  7th  segments  of  immature  larva,  lateral  view;  d,  caudal 
end  of  immature  larva.  After  King. 

Fig.  58.  Larva  of  Tabanus  sp .?  After  Griinberg. 

Fig.  59.  Early  stages  of  Tabanus  bovinus.  a,  Larva;  b,  pupa;  c,  anal  end  of 
larva;  d,  anal  end  of  pupa.  After  Degeer. 

Fig.  60.  Larva  of  Tabanus  ( Atylotus ) fulvus  (?).  a,  Entire  larva;  b,  head  and 
mouth-parts;  c,  one  proleg;  d,  segments  10,  11,  and  12  in  lateral  view.  After 
Sharp. 

Fig.  61.  Mature  larva  of  Tabanus  ditmiiatus.  After  Patton  and  Cragg. 

Fig.  62.  Mature  larva  of  Tabanus  bicallosus.  After  Patton  and  Cragg. 

Fig.  63.  Mature  larva  of  Tabanus  virgo.  After  Patton  and  Cragg. 

Fig.  64.  Larva  of  Tabanus  dit&niatus.  a,  Segments  3,  4,  and  5,  lateral  view; 
b,  segments  11  and  12,  lateral  view;  c,  segments  11  and  12,  ventral  view.  After 
King. 

Fig.  65.  Larva  of  Tabanus  kingi.  a,  Lateral  view  of  two  abdominal  segments; 
b,  one  proleg;  c,  ventral  side  of  anal  segment.  After  King. 


Plate  5. 


Fig.  66.  Caudal  end  of  larva  of  Tabanus  ustus,  lateral  view.  After  Neave 
(Terzi). 

Fig.  67.  Caudal  end  of  larva  of  Tabanus  corax , lateral  view.  After  Neave 
(Terzi). 

Fig.  68.  Caudal  end  of  larva  of  Tabanus  medionotatus , lateral  view.  After 
Neave  (Terzi). 

Fig.  69.  Caudal  end  of  larva  of  Tabanus  biguttatus,  lateral  view.  After  Neave 
(Terzi). 

Fig.  70.  Caudal  end  of  larva  of  Tabanus  variabilis,  lateral  view.  After  Neave 
(Terzi). 

Fig.  71.  Caudal  end  of  larva  of  Tabanus  maculatissimus,  lateral  view.  After 
Neave  (Terzi). 

Fig.  72.  Caudal  end  of  larva  of  Chrysops  longicornis,  lateral  view.  After 
Neave  (Terzi). 

Fig.  73.  Caudal  end  of  Chrysops.  Dorsal  view;  diagram.  After  Neave. 

Fig.  74.  Caudal  end  of  Hcematopota.  Dorsal  view;  diagram.  After  Neave. 

Fig.  75.  a,  b,  Larva  of  Tabanus  biguttatus.  Natural  size  42  mm.  After  King 
(colored  plate). 

Fig.  76.  a , Young  larva  of  Tabanus  sp.?  Colored  original  greenish  white. 
After  Maxwell-Leffroy  and  Howlett  (colored  plate),  b,  Full  grown  larva  of 
Tabanus  sp.}  Same  species  as  Fig.  76,  a.  Colored  original  yellow.  Natural 
size  47  mm.  After  Maxwell-Leffroy  and  Flowlett  (colored  plate),  c,  Hymen- 
opterous  parasite  of  same  larva.  After  Maxwell-Leffroy  and  Howlett  (colored 
plate). 

Fig.  77.  Head  and  first  segment  of  larva  of  Tabanus  atratus.  After  Malloch. 

Fig.  78.  Mandibles  of  larva  of  Tabanus  biguttatus.  After  King  (colored 
plate). 

Fig.  79.  Mandibles  of  larva  of  Tabanus  striatus.  After  Mitzmain  (photo- 
graph) 

Fig.  80.  Larval  stages  of  Tabanus  striatus.  a,  Newly  hatched  larvae;  b,  young 
larva  magnified;  c,  two  full  grown  larvae.  Natural  size  of  the  latter  34  mm. 
After  Mitzmain  (photograph). 

Fig.  81.  a,  b,  c,  Shed  skins  (exuviae)  of  three  different  larval  stages  of  Tabanus 
atratus  After  Mitzmain  (photograph). 


MONOGRAPH  NO.  13. 


PLATE  5. 


80 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  6. 


Fig.  82.  Early  stages  of  Hcematopota  pluvialis.  a,  Larva,  natural  size  13 
mm.;  b,  head  and  mouth-parts,  dorsal  view;  c,  head  and  mouth-parts,  lateral 
view;  d,  ventral  view  of  anal  segment;  e,  terminal  spiracle;  /,  pupa;  g,  pupal 
structure.  After  Perris. 

Fig.  83.  Stages  of  Hcematopota  pluvialis.  a,  Larva,  lateral  view,  natural 
size  14  mm.;  b,  terminal  spiracle  of  larva;  c,  pupa;  d,  terminal  segment  of  pupa. 
After  Brauer. 

Fig.  84.  Head  and  mouth-parts  of  Hcematopota  pluvialis.  ant,  antenna; 
Ir , labrum;  lb,  labium;  md,  mandible;  p,  palpus.  After  Brauer. 

Fig.  85.  Larva  of  Hcematopota  crudelis.  Natural  size  13  mm.  After  Neave 
(Terzi). 

Fig.  86.  Caudal  end  of  larva  of  Hcematopota  insatiabilis . After  Neave  (Terzi). 

Fig.  87.  Larva  of  Tabanus  spodopterus.  a,  Larva  magnified;  b,  dorsal  view, 
natural  size  45  mm.;  c,  lateral  view;  d,  caudal  end  of  larva;  e,  terminal 
spiracle;/,  head  of  larva,  lateral  view,  magnified.  After  Brauer. 

Fig.  88.  Larva  of  Tabanus  cordiger.  a,  Ventral  view  of  larva,  natural  size 
35  mm.;  b,  caudal  end;  c,  cross-section  through  segment;  d,  caudal  end  with 
tracheae. 

Fig.  89.  Larva  of  Hexatoma  pellucens.  a,  Dorsal  view  of  larva;  b,  dorsal 
view  of  last  three  segments  of  larva,  showing  pigmentation.  Natural  size  35  mm. 
After  Brauer. 

Fig.  90.  Head  and  mouth-parts  of  larva  of  Hexatoma  pellucens.  a,  Lateral 
view;  b,  lateral  view  of  mouth-parts;  c,  dorsal  view  of  head.  Ir,  labrum;  md, 
mandible;  p,  palpus;  ant,  antenna;  oc,  eye-spot;  lb,  labium.  After  Brauer. 

Fig.  91.  Head  of  larva  of  Hcematopota  pluvialis,  dorsal  view.  Parts  as  in 
Figs.  84  and  90.  After  Brauer. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  7. 


Fig.  92.  Full  grown  larva  of  Goniops  chrysocoma.  a,  Dorsal;  b,  ventral; 
c,  lateral  view.  Natural  size  17  mm.  After  McAtee  (photograph). 

Fig.  93.  Young  larva  of  Goniops  chrysocoma.  a , Entire  larva,  dorsal  view; 
b , mouth-parts,  magnified,  from  above;  c,  mouth-parts,  lateral  view.  After 
Walton. 

Fig.  94.  Full  grown  larva  of  Goniops  chrysocoma.  After  McAtee  (photo- 
graph). 

Fig.  95.  a,  b,  Structures  of  head  and  mouth-parts  of  the  full  grown  larva  of 
Goniops  chrysocoma.  anf,  base  of  antennae;  Ibr,  labrum;  mx,  maxilla;  mxp, 
maxilla  palpus.  Other  details  as  in  Figs.  84,  90,  91.  After  McAtee. 

Fig.  96.  a,  Larva  of  Tipula  oleracea  and  b,  Tabanus  ignotus?,  drawn  for  com- 
parison. After  del  Guercio.  (To  judge  from  the  figures,  both  drawings  seem 
to  represent  tipulid  larvae.) 

Fig.  97.  Head  of  Tabanus  albimedius,  lateral  view,  md,  mandible;  mx, 
maxilla;  ant,  antenna;  sp,  spines;  Ir,  labrum;  p,  palpus.  After  Patton  and 
Cragg. 

Fig.  98.  Intestinal  tract  of  the  full  grown  larva  of  Tabanus  albimedius.  ces, 
Esophagus;  pv,  proventriculus;  slg,  salivary  glands ; mg,  midgut;  mpt,  Malpi- 
ghian tubes.  After  Patton  and  Cragg. 


MONOGRAPH  NO.  13 


PLATE  7 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  8. 


Fig.  99.  Newly  hatched  larva  of  Tabanus  autumnalis  (?).  s 1 to  s 13,  somites 
(segments)  of  the  body;  w,  prolegs  armed  with  hooks;  tb,  touch-tactile  bristle; 
ph , pharynx;  md,  midgut;  ed,  hindgut;  ma,  Malpighian  vessels; a,  anus;  tr, tracheal 
trunks;  t sp,  terminal  spine;  g sup , upper, g inf , lower  cephalic  ganglion;  bg  1 to 
bg  11,  ventral  chain  of  ganglia;  ch  1 to  ch  3,  chordotonal  organs;  ot,  otocyst-like 
organs  on  posterior  border  of  anal  segment  (Graber’s  organ).  After  Graber. 

Fig.  100.  a,  Right  side  of  2nd  and  3rd  body  segments  of  young  Tabanus  larva 
highly  magnified. 

2nd  segment:  cu , cuticle;  ma , matrix;  m 1,  circular  muscles  of  pharynx; 
m 2,  muscles  originating  on  the  posterior  border  of  the  first  segment,  and  ex- 
tending forward  and  inwards,  possessing  strongly  marked  transverse  striation 
and  great  contractility;  hn , nerve  of  the  skin;  ekg,  mkg,  ganglion  cells  connected 
with  this  nerve  and  possessing  one  nucleus  ekg,  or  several  mkg ; tb,  tactile 
bristle;  s 2 ch  1 monoscolopic,  s 2 ch  2 triscolopic  chordotonal  organ;  li,  liga- 
ment; st  2,  rods;  efs,  terminal  filament;  e 1,  e 2,  e 3,  attachments  of  filaments; 
mn,  nerve  going  to  muscle;  tr,  branch  of  tracheal  system;  hg,  ganglion;  nu, 
nuclei. 

3rd  segment,  m 3,  system  of  sagittal  muscles,  freely  anastomizing,  and  in 
fresh  condition  smooth  (unstriated)  in  appearance;  bl,  region  of  integument  cov- 
ered with  bristles,  in  anterior  part  of  segment;  s 3 ch  1 to  s 3 ch  6 chordotonal 
organs  (taken  from  different  individuals);  ( ch  1 and  ch  2,  and  again  ch  4,  5,  and 
6 were  observed  in  the  same  individual) ; e 4,  e 5,  e 6,  points  of  attachments  of  the 
terminal  filaments  of  5 3 ch  5;  e 7,  e 8,  e 9,  those  oi  s 3 ch  2;  g inf,  lower  pharyn- 
geal ganglion.  After  Graber.  Zeiss  oil  immersion  lens. 

Fig.  100.  b,  Tactile  bristle  of  young  larva  of  Tabanus  autumnalis  (?),  with 
its  ganglion,  cu,  cuticle;  tb,  tactile  bristle,  articulating  on  its  place  of  attach- 
ment; ma,  matrix  (hypoderm),  in  fresh  condition  showing  no  cell  limits,  with 
reddish  nuclei;  starting  from  it  a fine  filament  torn  out  of  the  sheath  surround- 
ing the  bristle;  k,  nuclei;  n,  nerve;  g,  ganglion.  After  Graber.  Zeiss  oil 
immersion  lens. 

Fig.  101.  Triscolop  chordotonal  organ  of  the  2nd  segment  of  the  same 
larva,  n,  nerve;  g 1,  g 2,  g 3,  the  three  ganglion  cells,  lying  one  above  the  other, 
with  reddish  nuclei;  xfs,  neurit;  st,  rods;  ko,  heads  of  rods;  mk,  nucleus  of  the 
proximal  end;  dk,  of  the  distal  end  of  the  rod ; fs  1 to  fs  3,  the  three  terminal 
filaments.  After  Graber.  Zeiss  oil  immersion. 

Fig.  102.  Monoscolop  chordotonal  organ  of  the  2nd  segment  of  the  same  larva 
xfs,  neurit  visible  in  the  interior  of  the  rod.  After  Graber.  Zeiss  oil  immersion. 


MONOGRAPH  NO.  13. 


PLATE  8. 


101 


102 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  9. 


Fig.  103.  Larva  of  Tabanus  autumnalis  (?).  g,  Graber’s  organ.  After 
Graber. 

Fig.  104.  Posterior  end  of  larva,  magnified,  comprising  9th,  10th,  11th,  and 
12th  segments.  (In  the  original  the  numbers  are  given  erroneously  as  8,  9,  10, 
and  11.)  tr,  tracheal  trunks;  dv,  dorsal  vessel;  g,  Graber’s  organ;/,  terminal 
tube;  m,  two  muscles  extending  forward  from  Graber’s  organ.  After  Graber. 

Fig.  105.  Graber’s  organ  in  situ,  dv,  dorsal  vessel;  tr,  lateral  tracheal 
trunks;  fm,  muscle  of  dorsal  vessel;  m,  muscles;  t,  terminal  tube;  n,  nerves  (?); 
/,  fat  body;  cu,  cuticle  of  integument;  hp,  hypoderm.  X 60.  Zeiss  oil  immer- 
sion. After  Graber. 

Fig.  106.  The  organ  isolated,  cl  to  c3,  chitinous  capsules;  sp,  extremity  of 
capsule;  ep,  its  epithelium;  cp  1 to  cp  4,  pedunculate  bodies,  (in  the  original 
only  the  first  capsule  bears  this  name,  while  the  inner  ones  are  treated  as 
“internal  sacs”);  ml  to  m2,  muscles;  n to  n 1,  nerves  (?);  ga,  ganglion-like 
swelling  of  first  nerve;  t,  terminal  tube;  op,  operculum.  X 133.  Zeiss  oil 
immersion.  After  Graber. 

Fig.  107.  One  pair  of  pedunculate  bodies,  cp,  body;  st,  hollow  stem  or 
peduncle;  cu,  scaly  cuticle  to  which  they  are  fastened.  X 333.  Zeiss  oil  immer- 
sion. After  Graber. 

Fig.  108.  A portion  of  elastic  connective  tissue  from  the  surroundings  of  the 
organ,  after  treatment  with  boiling  KOH.  X 333.  Zeiss  oil  immersion.  After 
Graber. 

Graber’s  figures,  Figs.  103  to  108,  were  drawn  from  fresh  material. 


MONOGRAPH  NO.  13. 


PLATE  9. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  10. 


Fig.  109.  Young  larva  of  Tabanus  sp.?  tr,  tracheal  trunk;  g,  Graber’s  organ. 
After  Henneguy. 

Fig.  110.  Graber’s  organ,  enlarged,  of  larva  figured  in  Fig.  109.  After 
Henneguy. 

Fig.  111.  Larva  of  Tabanus  sp .?,  showing  the  location  of  Graber’s  organ  (the 
latter  drawn  larger  than  in  proportion  to  the  size  of  the  larva).  After  Paoli. 

Fig.  112.  Graber’s  organ  in  full  grown  larva  of  Tabanus  sp .?,  with  muscle 
and  nerves  attached  to  it.  cl  to  c 7,  capsules;  cp,  pedunculate  bodies;  m, 
muscle;  n,  nerve.  After  Paoli. 

Fig  113.  Hypothetical  diagram  of  the  development  of  Graber’s  organ,  c 1, 
first  capsule;  c 2,  second  capsule;  hp , hypoderm;  ct,  cuticle.  After  Paoli. 

Fig.  114.  Terminal  tube  of  Graber’s  organ,  hp,  hypoderm.  After  Paoli. 

Fig.  115.  Last  three segments  of  larva,  showing  Graber’s  organ  in  situ.  Dor- 
sal view  tr,  tracheal  trunk;  m 1,  muscles  of  the  first  pair;  a,  anal  tubercle. 
After  Paoli. 

Fig.  116.  Last  three  segments  of  larva,  with  Graber’s  organ.  Lateral  view. 
m 2,  muscle  of  the  second  pair;  t,  terminal  tube.  Other  details  as  in  Fig.  115. 
After  Paoli. 

Fig.  117.  Young  larva  of  Tabanus  quatuornotatus . After  Lecaillon. 

Figs.  118  and  119.  Posterior  end  of  body  of  larva  of  Tabanus  quatuornotatus, 
somewhat  older  than  that  figured  in  Fig.  117,  showing  the  pedunculate  bodies 
being  expelled  through  the  terminal  tube.  After  Lecaillon. 

Fig.  120.  Dorsal  view  of  Segments  11  and  12  (syphon)  of  a young  larva 
Tabanus  corax , showing  Graber’s  organ;  the  dotted  lines  show  the  position  of  the 
anus.  After  Neave. 


MONOGRAPH  NO.  13. 


PLATE  10. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  11. 


Fig.  121.  Pupa  of  Goniops  chrysocoma.  a , Dorsal;  b,  ventral;  c,  lateral  view. 
After  McAtee. 

Fig.  122.  Pupa  of  Tipula  oleracea.  After  Paoli. 

Fig.  123.  Pupa  of  Tabanus  ignotus.  Compare  with  Fig.  122.  After  Paoli. 
(See  also  Fig.  96,  a,  b.  No  resemblance  is  found  in  the  pupae  which  indicates 
that  Fig.  96,  b,  does  not  represent  a tabanid  larva.) 

Fig.  124.  Pupa  of  Tabanus  atratus.  Natural  size  31  mm.  After  Hine. 

Fig.  125.  Pupa  of  Tabanus  stygius.  Natural  size  28  mm.  After  Hine. 

Fig.  126.  Pupa  of  Tabanus  sulcijrons.  Natural  size  27  mm.  After  Hine. 

Fig.  127.  Pupa  of  Tabanus  lasiophthalmus.  Natural  size  23  mm.  After 

Hine. 

Fig.  128.  Pupa  of  Tabanus  vivax.  Natural  size  23  mm.  After  Hine. 

Fig.  129.  Pupa  of  Tabanus  ditceniatus . After  King. 

Fig.  130.  Pupa  of  Chrysops  longicornis.  Natural  size  11  mm.  After  Neave 
(Terzi). 

Fig.  131.  Pupa  of  Hcematopota  insatiabilis.  Natural  size  11  mm.  After 

Neave  (Terzi). 

Fig.  132.  Pupa  of  Tabanus  sp.?  Natural  size  18  mm.  After  Maxwell- 
Leffroy  and  Howlett. 

Fig.  133.  Pupa  of  Tabanus  ditceniatus.  Ventral  view.  After  Patton  and 
Cragg. 

Fig.  134.  Pupa  of  Tabanus  virgo.  Ventral  view.  After  Patton  and  Cragg. 
Fig.  135.  Pupa  of  Tabanus  bicallosus.  Ventral  view.  After  Patton  and 
Cragg. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  12. 


Fig.  136.  Pupa  of  Tabanus  cordiger.  After  Picard  and  le  Blanc  (from  pupal 
shell). 

Fig.  137.  a , Pupa  of  Tabanus  kingi;  b,  caudal  end,  lateral  view;  c,  caudal  end, 
ventral  view.  After  King. 

Fig.  138.  Pupa  of  Tabanus  variabilis.  Natural  size  20  mm.  After  Neave 
(Terzi). 

Fig.  139.  Pupa  of  Tabanus  sp .?  (see  Figs.  7 and  76).  Colors  of  original  yel- 
low, thorax  grayish.  Natural  size  21  mm.  After  Maxwell-Leffroy  and  Howlett 
(colored  plate). 

Fig.  140.  Pupa  shell  of  Tabanus  atratus.  Natural  size  31  mm.  After  C.  V. 
Riley. 

Fig.  141.  Caudal  end  of  pupa  of  Tabanus  ditccniatus . a,  Lateral  view;  b, 
ventral  view.  After  King. 

Fig.  142.  Pupa  of  Tabanus  par.  a , Entire  pupa,  lateral  view,  natural  size 
22  mm.;  b,  pupal  aster.  After  King  (colored  plate). 

Fig.  143.  Pupal  aster  of  Tabanus  striatus.  a,  Pupal  aster  of  male;  b,  pupal 
aster  of  female.  After  Mitzmain  (photograph). 

Fig.  144.  Pupal  aster  of  Tabanus  bicallosus  d.  After  Patton  and  Cragg. 

Fig.  145.  Pupal  aster  of  Tabanus  bicallosus  $ . After  Patton  and  Cragg. 

Fig.  146.  Pupal  aster  of  Tabanus  virgo.  After  Patton  and  Cragg. 

Fig.  147.  Pupal  aster  of  Tabanus  ditceniatus.  After  Patton  and  Cragg. 

Fig.  148.  Pupal  aster  of  Tabanus  biguttatus.  After  King  (colored  plate). 

Fig.  149.  Pupa  of  Tabanus  lineola,  dorsal  view.  After  Malloch. 

Fig.  150.  Pupa  of  Tabanus  sp.?,  natural  size  17  mm.  After  Surcouf  and 
Ricardo. 

Fig.  151.  Pupa  of  Tabanus  bromius  d in  process  of  hatching,  natural  size  23 
mm.  After  Surcouf  and  Ricardo. 

Fig.  152.  Pupa  of  Tabanus  striatus.  a,  Lateral  view  of  pupa;  b,  pupa  in 
process  of  hatching.  After  Mitzmain. 


MONOGRAPH  NO.  13. 


PLATE  12. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  13. 


Fig.  153.  Upper  half  of  thorax  of  pupa  of  Tabanus  siygius,  dorsal  view.  After 
Malloch. 

Fig.  154.  Upper  half  of  thorax  of  pupa  of  Chrysops  vittatus,  dorsal  view. 
After  Malloch. 

Fig.  155.  Thorax  of  pupa  of  Tabanus  cordiger,  dorsal  view.  After  Picard  and 
le  Blanc. 

Fig.  156.  Prothoracic  spiracle  of  pupa  of  Tabanus  nigrescens,  dorsal  view. 
After  Malloch. 

Fig.  157.  Prothoracic  spiracle  of  pupa  of  Chrysops  vittatus , dorsal  view. 
After  Malloch. 

Fig.  158.  Pupal  aster  of  Tabanus  cordiger.  After  Picard  and  le  Blanc. 

Fig.  159.  Pupal  aster  of  Tabanus  Iasi  op  hthalmus.  After  Hine. 

Fig.  160.  Pupal  aster  of  Tabanus  vivax.  After  Hine. 

Fig.  161.  Pupal  aster  of  Tabanus  stygius.  After  Hine. 

Fig.  162.  Pupal  aster  of  Tabanus  lineola.  After  Hart  (photograph). 

Fig.  163.  Pupal  aster  of  Tabanus  atratus.  After  Hart  (photograph). 

Fig.  164.  Pupal  aster  of  Tabanus  atratus.  After  Hine. 

Fig.  165.  Pupal  aster  of  Tabanus  sulcifrons.  After  Hine. 

Fig.  166.  Pupal  aster  of  Chrysops  magnifica,  var.  inornata.  a,  Male;  b, 
female.  After  Neave  (Terzi). 

Fig.  167.  Pupal  aster  of  Chrysops  bimaculosa.  a,  Male;  b,  female;  c,  female, 
side  view.  After  Neave  (Terzi). 

Fig.  168.  Pupal  aster  of  Chrysops  wellmani.  a,  &\b,  9.  After  Neave. 

Fig.  169.  a,  Pupal  aster  and  b,  dorsolateral  comb  of  Hcematopota  decora  $ . 
After  Neave. 

Fig.  170.  Pupal  aster  of  Hcematopota  crudelis.  After  Neave. 

Fig.  171.  Pupal  aster  of  Chrysops  longicornis.  a , c ?;b,  9.  After  Neave. 
Fig.  172.  Pupal  aster  of  Hcematopota  insatiabilis  9.  a,  From  behind;  b , 
side  view;  c,  dorsolateral  comb.  After  Neave. 


MONOGRAPH  NO.  13. 


PLATE  13. 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  14. 


Fig.  173.  Tabanus  atrimanus.  a,  Pupal  aster  of  cP;  b,  dorsolateral  comb  of 
$ ; c,  pupal  aster  of  9 . After  Neave  (Terzi). 

Fig.  174.  Tabanus  medionotatus  cP.  a , Pupal  aster;  b,  profile  of  last  seg- 
ment of  pupa.  After  Neave  (Terzi). 

Fig.  175.  Tabanus  biguttatus.  a,  Pupal  aster  of  cP  and  b,  of  $ ; c,  dorso- 
lateral comb  of  cP  and  d,  of  9 . After  Neave  (Terzi). 

Fig.  176.  Tabanus  variabilis.  a,  Pupal  aster  of  cP;  b,  dorsolateral  comb  of 
cP;  c,  dorsolateral  comb  of  9 ; d,  pupal  aster  of  9 . After  Neave  (Terzi). 

Fig.  177.  Tabanus  ustus.  a,  Dorsolateral  comb  of  cP;  b,  pupal  aster  o cP; 
c , dorsolateral  comb  of  9 (with  six  spines).  After  Neave  (Terzi). 

Fig.  178.  Tabanus  maculatissimus.  a and  b,  dorsolateral  comb  of  two  dif- 
ferent cP  ; c,  pupal  aster  of  9 ; d,  dorsolateral  comb  of  9 . After  Neave  (Terzi). 


MONOGRAPH  NO.  13.  PLATE  14. 


178 


(Marchand:  The  early  stages  of  Tabanidae.) 


Plate  15. 


Fig.  179.  Tabanus  nagamiensis  d.  a,  Pupal  aster;  b,  pupal  aster  from  the 
side,  showing  combs,  the  dorsolateral  comb  being  absent.  After  Neave  (Terzi). 

Fig.  180.  a,  Pupal  aster  of  Tabanus  desertus;  b,  lateral  view.  After  Bodkin 
and  Cleare  (Terzi). 

Fig.  181.  Tabanus  corax.  a,  Pupal  aster  of  d)b,  pupal  aster  of  $ ; c,  dorso- 
lateral comb  of  $.  After  Neave  (Terzi). 

Fig.  182.  Tabanus  f rater nus  $.  u,  Pupal  aster;  b,  dorsolateral  comb.  After 
Neave  (Terzi). 

Fig.  183.  Tabanus  obscuripes  d.  cl,  Pupal  aster;  b,  profile  of  last  segment 
of  pupa.  After  Neave  (Terzi). 

Fig.  184.  Tabanus  insignis.  a,  Dorsolateral  comb  of  d ;b,  pupal  aster  of  d; 
c,  dorsolateral  comb  of  $ . After  Neave  (Terzi). 

Fig.  185.  Tabanus  laverani  9.  a,  Pupal  aster;  b,  enlarged  view  of  dorso- 
lateral comb;  c,  pupal  aster  from  the  side,  showing  the  combs  and  the  small 
dorsolateral  comb.  After  Neave  (Terzi). 

Fig.  186.  Tabanus  gratus.  a , Dorsolateral  comb  of  d;  b,  pupal  aster  of  d ; 
c and  d , dorsolateral  comb  of  two  different  $ . After  Neave  (Terzi). 


MONOGRAPH  NO.  13. 


PLATE  15. 


(Marchand:  The  early  stages  of  Tabanidfe.) 


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